MikaStars39/nano-eval huggingface dataset:
What are the graphite deposits that are formed by causing significant changes in the material composition and structure of bituminous coal called?

Options:
A. Metamorphic rock formations
B. Sedimentary ore deposits
C. Metamorphic organic deposits
D. metamorphic ore deposits
E. Sedimentary deposits
F. Metamorphic mineral deposits
G. Organic residue deposits
H. Magmatic deposits
I. Sedimentary mineral deposits
J. Thermal mineral deposits
Answer: D
Which types of mineral resources are in severe shortage in China?

Options:
A. Tungsten, lead, zinc, etc.
B. Chromium, lead, zinc, diamond, etc.
C. Chromium, nickel, diamond, manganese, etc.
D. Platinum, rare earths, diamond, nickel, etc.
E. Chromium, platinum, diamond, potassium salt, and diamond etc.
F. Chromium, rare earths, diamonds, etc.
G. Tungsten, platinum, diamonds, silver, etc.
H. Chromium, tungsten, diamond, magnesium, etc.
I. Chromium, platinum, copper, diamond, etc.
J. Chromium, platinum, diamond, iron ore, etc.
Answer: E
In which of the following types of rock does the P-wave propagate the fastest?

Options:
A. Slate.
B. Limestone.
C. Granite.
D. Gabbro.
E. Interbedded sandstone and shale.
F. Quartzite.
G. Basalt.
H. Unconsolidated sediments.
I. Marble.
J. Peat.
Answer: D
When did true land plants first appear?

Options:
A. Triassic
B. Jurassic
C. Cambrian
D. Ordovician
E. Cretaceous
F. Devonian
G. Pleistocene
H. Silurian
I. Carboniferous
J. Permian
Answer: H
What was the first land plant to appear on Earth?

Options:
A. Prionophyta
B. Protofungia
C. Gymnospermia
D. Bryophytema
E. Pteridophyta
F. Mouldosperma
G. Gymnomossia
H. Floridophyta
I. Bryophytina
J. Algalophyta
Answer: C
The chemical composition classification of igneous rocks is divided into four categories based on SiO ₂ content: ultrabasic rocks, basic rocks, neutral rocks, and acidic rocks. What is the SiO ₂ content (in wB/%) in each category?

Options:
A. <40%, 40-53%, 53-66%, >66%
B. <43%, 43-55%, 55-68%, >68%
C. <47%, 47-55%, 55-67%, >67%
D. <44%, 44-52%, 52-65%, >65%
E. <40%, 40-52%, 52-65%, >65%
F. <45%, 45-53%, 53-66%, >66%
G. <40%, 40-50%, 50-63%, >63%
H. <42%, 42-51%, 51-64%, >64%
I. <46%, 46-54%, 54-67%, >67%
J. <50%, 50-58%, 58-70%, >70%
Answer: F
What are the four types of terrigenous clastic rocks?

Options:
A. Shale, siltstone, mudstone, limestone
B. Gneiss, schist, soapstone, slate
C. Quartzite, flint, chert, rock salt
D. Conglomerate, shale, breccia, sandstone
E. Shale, quartzite, marble, travertine
F. Basalt, andesite, rhyolite, dacite
G. Granite, basalt, limestone, dolomite
H. Chalk, flint, jasper, obsidian
I. Conglomerate, sandstone, siltstone, argillaceous rocks
J. Claystone, limestone, quartzite, marble
Answer: I
Porphyry and matrix of porphyritic structure are mostly formed in the () generation; porphyritic-like structure of porphyritic crystal and matrix are basically the products of the () generation.

Options:
A. Different, Same
B. First, Intermediate
C. First, Second
D. Original, Final
E. Early, Late
F. Same, Different
G. Third, Fourth
H. Initial, Terminal
I. Initial, Following
J. Primary, Secondary
Answer: A
What are the three common types of intergrowth in structures?

Options:
A. Ball joint, Fusion joint, Expansion joint
B. Elastic joints, Rigid joints, Flexible joints
C. Pigment blend, Material mix, Structural scheme
D. Graphic texture, Perthitic texture, Myrmekitic texture
E. Scalar connection, Vector bond, Matrix linkage
F. Conductive joint, Resistive joint, Capacitive joint
G. Chromatic pattern, Granular formation, Coarse arrangement
H. Vector joints, Matrix joints, Tensor joints
I. Frictional lock, Magnetic attachment, Fluid coupling
J. Pin joint, Rolling joint, Sliding joint
Answer: D
What is a fold whose inner and outer arc curvatures are the same, and has isoclinal lines of equal length?

Options:
A. Similar Folds
B. Flimsy pleated wrinkles
C. Equal arc bends
D. Even twist contours
E. Homogeneous loop twists
F. Parallel folds
G. Consistent flex ribbons
H. Uniform crease curves
I. isopach fold
J. Identical curl arcs
Answer: I
Neutral folding action results in unchanged thickness on the vertical plane at every point of the fold. Which of the following descriptions typifies this folding pattern?

Options:
A. Alternate folds
B. Consecutive wrinkles
C. Parallel folds
D. Similar Folds
E. Top-Thin Wrinkles
F. Evened wrinkles
G. Thick Folds
H. Continuous layers
I. Equipartite layers
J. Matched folds
Answer: C
The chemical composition Na2O+K2O in magmatic rocks is called ().

Options:
A. Total silicate content
B. Total alkali content
C. Total oxide density
D. Total sulphate composition
E. Total magnesium levels
F. Total alkali composition
G. Total carbonate values
H. Total silica levels
I. Total alkali mass
J. Total basalt components
Answer: B
Where is the genital opening of the river mussel?

Options:
A. water chamber
B. dorsal aperture
C. cephalic space
D. external shell
E. epibranchial cavity
F. heart sinus
G. brachial chamber
H. abdominal cavity
I. visceral pouch
J. lateral channel
Answer: E
The shell of the mollusk is divided into the cuticle, shell layer, and what else from the outside to the inside?

Options:
A. Dermis layer
B. Pearl layer
C. Chitinous layer
D. Muscular layer
E. Connective tissue
F. Cartilage layer
G. Epidermis layer
H. Mantle layer
I. Protective layer
J. Crystalline layer
Answer: B
What is the type of vertebral body of the cervical vertebrae of birds?

Options:
A. Triangular type
B. Rectangular type
C. Elongated type
D. Oval type
E. Concave type
F. Flat type
G. Rounded type
H. Square type
I. Convex type
J. Cylindrical type
Answer: E
What types of vertebrate kidneys can be divided into and what are they?

Options:
A. Holonephros, pronephros, dorsal nephros, mesonephros, metanephros
B. Metanephros, pronephros, mesonephros, diurnephros, nephros
C. Holonephros, pronephros, mesonephros, metanephros, archinephros
D. Pronephros, mesonephros, metanephros, postnephros, holonephros
E. Holonephros, pronephros, metanephros, mesonephros, diurnephros
F. Pronephros, mesonephros, holonephros, metanephros, archinephros
G. Metanephros, mesonephros, pronephros, nephros, holonephros
H. Mesonephros, pronephros, metanephros, archinephros, nephros
I. Pronephros, metanephros, diurnephros, mesonephros, holonephros
J. Holonephros, archinephros, pronephros, mesonephros, metanephros
Answer: A
What kind of reproduction method does Paramecium belong to?

Options:
A. Vegetative propagation
B. Conjugation
C. Budding
D. Parthenogenesis
E. Binary fission
F. Sporulation
G. Spore formation
H. Regeneration
I. Fragmentation
J. Sexual reproduction
Answer: B
What is the approximate time required for sperm production in the body?

Options:
A. One week
B. Three weeks
C. Two months
D. Six weeks
E. Five weeks
F. Eight weeks
G. Four weeks
H. Three months
I. One month
J. One day
Answer: C
Which of the following statements about sweating in the body is correct?

Options:
A. Sweating is inhibited by high temperatures
B. Excessive sweating can cause isotonic dehydration
C. Excessive sweating can cause hypotonic dehydration
D. Sweat glands are only found in the armpits and groin
E. The primary component of sweat is glucose
F. Excessive sweating can cause hypertonic dehydration
G. Sweating is primarily controlled by the parasympathetic nervous system
H. Sweating is an excretory function of the liver
I. The sweating center is located in the medulla oblongata
J. The nerve that controls the small sweat glands is the vagus nerve
Answer: F
What may occur during rapid intravenous infusion of saline?

Options:
A. Increased renal tubular reabsorption
B. Increased blood pressure in the glomerular capillaries
C. Increased pressure in the renal capsule
D. Decreased plasma colloid osmotic pressure
E. Decreased blood pressure in the glomerular capillaries
F. Decreased blood volume
G. Increased blood viscosity
H. Decreased cardiac output
I. Increased plasma colloid osmotic pressure
J. Increased heart rate variability
Answer: D
Which of the following factors increases the glomerular filtration rate?

Options:
A. Decreased plasma colloid osmotic pressure.
B. Decreased afferent arteriolar diameter.
C. Increased Bowman's capsule hydrostatic pressure.
D. Increased efferent arteriolar constriction.
E. Decreased plasma flow in the glomerulus.
F. Increased colloid osmotic pressure in the filtrate.
G. Increased afferent arteriolar resistance.
H. Decreased renal sympathetic nerve activity.
Answer: A
In cellular interactions, the primary interactions are between proteins and ___ as well as proteins and ___.

Options:
A. Steroids, fibers
B. Nucleic acids, lipids
C. Hormones, minerals
D. Carbohydrates, nucleic acids
E. Enzymes, vitamins
F. Lipids, nucleic acids
G. Lipids, carbohydrates
H. Proteins, lipids
I. Vitamins, steroids
J. Proteins, carbohydrates
Answer: J
In an experiment to determine the vitamin C content of a sample using 2,6-dichlorophenol indophenol, the end point of the titration is when the sample is ___by titration with a ___ 2,6_-dichlorophenol indophenol solution.

Options:
A. Black, red
B. White, pink
C. Yellow, green
D. Orange, yellow
E. Purple, orange
F. Grey, blue
G. Lavender, grey
H. Brown, purple
I. Blue, clear
J. Roses, none
Answer: J
As proteins pass through the Sephadex column, the order in which proteins are eluted from the column is ___.

Options:
A. Proteins with higher molecular weights are eluted first
B. Proteins with lower molecular weights are eluted first
C. Proteins with differing molecular diameters are sorted first
D. Proteins are arranged by secondary structures first
E. Proteins with similar molecular weights are eluted together
F. Proteins are sorted by tertiary structures first
G. Proteins with equal molecular weights are eluted last
H. Proteins with reversible binding properties are eluted first
I. Proteins with intermediate molecular weights are eluted first
J. Proteins with varying molecular weights are eluted randomly
Answer: A
The two different pathways for the synthesis of lecithin in organisms are ___ and ___.

Options:
A. Cellular integration route, CMP-choline process
B. Phospholipid biosynthesis, choline phosphotransferase method
C. Cholesterol synthase process, CMP-glycerol pathway
D. Lecithin precursor route, CDP-choline pathway
E. Glycerol diester pathway, CDP-glycerol diester pathway
F. Fatty acid process, glycerol-phosphate pathway
G. Ether lipid cycle, CDP-ethanolamine method
H. Lipid transfer sequence, CDP-lipid transfer method
I. Cell membrane route, phosphatidylcholine synthesis
J. Glycerol ester cycle, CMP-glycerol ester process
Answer: E
The primary mycelium of basidiomycetes is composed of monokaryotic cells, while______ is composed of dikaryotic cells.

Options:
A. The mycelial network
B. The reproductive mycelium
C. The primary hyphae
D. The diploid mycelium
E. The secondary mycelium
F. The submycelium
G. The aerial mycelium
H. The tertiary mycelium
I. The spore-forming mycelium
J. The vegetative mycelium
Answer: E
In cereal crops like rice and wheat, the tissues utilized by humans are primarily_________. In contrast, fiber crops such as ramie utilize _______.

Options:
A. Vascular tissues; photosynthetic tissues.
B. Xylem tissues; phloem tissues.
C. Storage tissues; photosynthetic tissues.
D. Photosynthetic tissues; parenchyma tissues.
E. Fundamental tissues; sclerenchyma tissues.
F. Phloem tissues; collenchyma tissues.
G. Parenchyma tissues; mechanical tissues.
H. Ground tissues; vascular tissues.
I. Epidermal tissues; storage tissues.
J. Sclerenchyma tissues; epidermal tissues.
Answer: G
What happens when the output of the right heart is multiplied?

Options:
A. Pulmonary blood volume increased and pulmonary artery pressure decreased significantly
B. Increased pulmonary blood volume and slightly decreased pulmonary artery pressure
C. Decreased pulmonary blood volume and slight increase in pulmonary artery pressure
D. Decreased pulmonary blood volume and significant decrease in pulmonary artery pressure
E. Pulmonary blood flow increases and pulmonary valve pressure decreases slightly
F. Pulmonary blood volume decreases and pulmonary artery pressure increases significantly
G. Increased pulmonary blood volume and significant decrease in pulmonary artery pressure
H. Pulmonary blood volume increases and pulmonary artery pressure increases significantly
I. Increased pulmonary blood volume and slight increase in pulmonary artery pressure
J. Decreased pulmonary blood volume and slightly decreased pulmonary artery pressure
Answer: I
Generally speaking, how does the ratio of free water to bound water change in the tissues of overwintering crops during the winter?

Options:
A. Dip slightly
B. Remain stable
C. Peak
D. Elevate
E. Increase significantly
F. Heighten
G. Decrease slightly
H. Reduce
I. Fluctuate
J. Little change
Answer: H
What is the main reason why introducing winter wheat from the north to be cultivated in Guangdong fails to produce grain-bearing ears?

Options:
A. Frequent rainfall
B. Excessive flooding
C. High temperature
D. Inadequate water supply
E. Strong illumination
F. Reduced air humidity
G. Early frost occurrence
H. Low soil fertility
I. Short daylight hours
J. Increased pests
Answer: C
What should be used for the treatment of dysbiosis?

Options:
A. Antitoxin
B. Vitamins
C. Toxoid
D. Probiotic Yogurt
E. Fungal Medication
F. Balanced Diet
G. Antibiotics
H. Ecological Formulation
I. Herbal Supplements
J. Synthetic Drugs
Answer: H
The starchiness (A) gene in corn seeds is dominant over the sugary gene (a). When a pure sugary corn's pistil receives starch-containing pollen, the genotype of the endosperm in the seeds it produces is ___.

Options:
A. AA
B. Aa
C. AAa
D. aaa
E. AAA
F. aaaa
G. AAaa
H. Aaa
I. AaA
J. AAAAA
Answer: H
A male sterile line of a plant was examined and found to have pollen in the male flowers but was sterile. When it was crossed with a restorer line, all the hybrid plants were pollen dispersing and all the pollen was fertile, and when it was backcrossed with the sterile line, the backcross population showed a 1:3 separation of fertile and sterile plants. The sterile lines were associated with ___ pairs of nuclear genes.

Options:
A. 8
B. 4
C. 5
D. 10
E. 7
F. 1
G. 9
H. 3
I. 6
J. 2
Answer: J
The proportions of ___ bases that make up DNA vary depending on the species of organism.

Options:
A. A+C/T+G
B. A/T
C. A+G/C+T
D. G+C/A+T
E. G+T/C+A
F. C/G
G. T/A
H. T+C/A+G
I. G/C
J. A+C/G+T
Answer: D
In someone's oral epithelial cells, two $\mathbf{X}$ chromatin can be observed and $\mathbf{Y}$ chromatin is positive, indicating that their sex chromosome composition is ___.

Options:
A. XXX
B. XYY
C. YYY
D. XXXY
E. XY
F. XXYYY
G. XXY
H. XX
I. XXXXY
J. XXYY
Answer: G
The pattern of expression of heritability is that traits that are less susceptible to environmental influences have a higher heritability than ___, traits that are susceptible to environmental influences have a higher heritability than ___, traits with a small coefficient of variation have a higher heritability than ___, and traits with a large coefficient of variation have a higher heritability than ___.

Options:
A. Low, high, high, low
B. High, low, low, high
C. Low, low, high, high
D. Low, high, low, high
E. High, low, high, low
F. Medium, low, high, medium
G. Medium, high, medium, low
H. High, high, low, low
I. High, medium, low, high
J. Low, medium, high, medium
Answer: E
The base composition of a single-stranded positive-sense DNA is A 21%, G 29%. After replication, the base composition of A and G in the product catalyzed by RNA polymerase transcription is ___ and ___.

Options:
A. 30%, 28%
B. 21%, 29%
C. 26%, 24%
D. 22%, 28%
E. 19%, 31%
F. 20%, 30%
G. 29%, 21%
H. 25%, 25%
I. 27%, 23%
J. 24%, 26%
Answer: B
Where do the edible parts of apples and other pears mainly come from?

Options:
A. Stem
B. Bark
C. Petals
D. Trunk
E. Leaves
F. Fruit core
G. Flower tube
H. Branches
I. Roots
J. Seeds
Answer: G
Two whorls of perianths have no distinction in color, shape, etc., such as lily flowers, what is called?

Options:
A. pseudochlamydeous
B. polychlamydeous
C. isochlamydeous
D. monochlamydeous
E. amphichlamydeous
F. trichlamydeous
G. heterochlamydeous
H. dichlamydeous
I. homochlamydeous
J. acyclochlamydeous
Answer: I
Which of the following subphyla of ferns has a mycorrhizal gametophyte?

Options:
A. Ginkgophyta
B. Bryophyta
C. Lycophyta
D. Pteridophyta
E. Hepaticophyta
F. Magnoliophyta
G. Cycadophyta
H. Coniferophyta
I. Anthophyta
J. Psilophyta
Answer: C
What are the characteristics of the Juglandaceae that adapt to wind pollination?

Options:
A. Unisexual flowers
B. Heavy, sticky pollen
C. Small, inconspicuous flowers
D. Thick, fleshy fruit
E. Brightly colored sepals
F. Large colorful petals
G. Long, slender stems
H. Sweet-smelling nectar
Answer: A
What is the vascular bundle of pumpkin?

Options:
A. Interwoven vascular structure
B. Conducive vascular unit
C. Jointed vascular conduit
D. Double-layered vascular strand
E. Fiber-rich vascular network
F. Hollow vascular framework
G. Essential vascular system
H. Kinetically active vascular chain
I. Bi-tough vascular bundle
J. Ground tissue vascular bundle
Answer: I
Which of the following scientists strongly opposed Fourier's research paper?

Options:
A. Laplace
B. Huygens
C. Leibniz
D. Fermat
E. Gauss
F. Newton
G. Lagrange
H. Pascal
I. Descartes
J. Euler
Answer: G
There is a deep groove ball bearing with a basic rated life of 8000h, when its load is increased by 1 times, and the speed is 12 of the original speed, other conditions remain the same, then how long is the basic rated life of the bearing?

Options:
A. 16000h
B. 12000h
C. 6000h
D. 3200h
E. 8000h
F. 14000h
G. 4000h
H. 10000h
I. 2400h
J. 2000h
Answer: J
In stress variation, if there is a difference in either the cycle, stress amplitude, or mean stress, what is it called?

Options:
A. Non-constant changing stress
B. Uniform cyclic stress modification
C. Constant amplitude stress change
D. Periodic mean stress deviation
E. Fluctuating cyclic stress adjustment
F. Regular varying mean pressure
G. Steady differential stress adjustment
H. Continuous mean stress adaptation
I. Non-steady varying stress
J. Irregular stress amplitude shift
Answer: I
The profile dimensions of keys are usually selected from standards based on what criteria?

Options:
A. The length of the groove
B. The diameter of the shaft
C. The radius of the spline
D. The diameter of the groove
E. The height of the collar
F. The width of the collar
G. The thickness of the notch
H. The thickness of the key
I. The height of the keyways
J. The depth of the notches
Answer: B
Where is the calculation point for the bending fatigue strength of the tooth root?

Options:
A. The calculation point for the bending fatigue strength of the tooth root is at the tensile section of the risk cross-section of the tooth root.
B. The calculation point for the bending fatigue strength of the tooth root is at the center point of the tooth root apex.
C. The calculation spot for the bending fatigue strength of the tooth root is at the compression side of the critical cross-section of the tooth root.
D. The calculation point for the bending fatigue strength of the tooth root is at the base section of the safety cross-section of the tooth root.
E. The analysis point for the bending fatigue strength of the tooth root is at the tension side of the critical cross-section of the tooth root.
F. The calculation point for the bending fatigue strength of the tooth root is at the compression section of the danger cross-section of the tooth root.
G. The evaluation point for the bending fatigue strength of the tooth root is at the shear center of the critical cross-section of the tooth root.
H. The calculation point for the bending fatigue strength of the tooth root is at the lateral edge of the danger cross-section of the tooth root.
I. The calculation point for the bending fatigue strength of the tooth root is at the tension section of the danger cross-section of the tooth root.
J. The evaluation area for the bending fatigue strength of the tooth root is at the neutral line of the critical cross-section of the tooth.
Answer: I
The sampler and hold circuit only affects which aspect of the open-loop pulse transfer function?

Options:
A. Signals
B. Zeros
C. Axes
D. Poles
E. Nodes
F. Roots
G. Arguments
H. Magnitudes
I. Constants
J. Coefficients
Answer: B
What is constant flow?

Options:
A. Flow changes according to a certain pattern over time
B. Movement of particles remains consistent over periods
C. Temperature at any single point varies periodically
D. Density alterations occur randomly over time
E. Particle movement is unpredictable in direction
F. Migration acceleration is zero
G. The velocity distribution of each overcurrent section is the same
H. The elements at each spatial point do not change over time
I. Fluid speed increases linearly with time
J. Pressure remains constant throughout the system
Answer: H
How should water flow in a certain direction?

Options:
A. Flow from areas with more fluid temperature to areas with less fluid temperature
B. Flow from areas with high flow velocity to areas with low flow velocity
C. Flow from areas with high pressure to areas with low pressure
D. Flow from areas with high water purity to areas with low water purity
E. Flow from areas with high fluid density to areas with low fluid density
F. Flowing from high to low
G. Flow from areas with low mechanical energy per unit weight of fluid to areas with high mechanical energy
H. Flow from areas with low flow velocity to areas with high flow velocity
I. Flow from areas with high mechanical energy per unit weight of fluid to areas with low mechanical energy
J. Flow from areas with increased fluid volume to areas with decreased fluid volume
Answer: I
What happens to streamlines and streamlines under normal circumstances?

Options:
A. Can sometimes be tangent, usually intersect
B. Must intersect and diverge accordingly
C. Can only be tangent, but cannot intersect
D. Can intersect, can also be tangent
E. Often parallel, rarely intersecting
F. Neither intersecting nor tangent
G. Can converge, but usually intersect
H. Can only divide, but not converge
I. Can only intersect, but cannot be tangent
J. Tend to merge, seldom being parallel
Answer: C
According to the concept of continuous media, what does a fluid particle refer to?

Options:
A. Against fluid capacity, geometric proportions are extensively tiny but encapsulate a numerous amount of molecules
B. Relative to fluid dimensions, geometric sizes are incredibly small and encompass numerous molecules in microelements
C. Relative to fluid volume, geometric dimensions are impressively large yet hold an excessive number of molecules
D. Compared to fluid mass, geometric dimensions are moderately small and hold a medium number of molecules
E. Compared to fluid space, geometric dimensions are extremely small and contain a large number of molecules in microelements
F. In relation to fluid volume, geometric proportions are significantly large and include few molecules within microelements
G. Geometric points
H. Solid particles inside the fluid
I. Molecules of fluids
J. Relative to fluid area, geometric dimensions are considerably tiny but hold a minimal number of molecules
Answer: E
If the working fluid undergoes a variable process of heat absorption, temperature rise, and pressure drop, then the variable index is ().

Options:
A. n<0
B. n>k
C. 0<n<1
D. 1<n<k
E. n→∞
F. n≥k
G. 1<n<2
H. n=1
I. n≤k
J. n=0
Answer: C
What is the pattern of any reverse cycle on the T-s diagram?

Options:
A. The ratio of heat absorption to release is 1:1
B. Heat absorption equals heat release
C. Heat absorption surpasses heat release consistently
D. The heat release surpasses absorption at intervals
E. Heat absorption is less than heat release
F. Heat absorption is greater than heat release
G. The relationship between heat absorption and release is uncertain
H. Heat release and absorption maintain a proportional balance
I. The heat release equals the heat absorption continuously
J. The heat absorption and release show a random pattern
Answer: E
What is the average velocity at each point on the retention section?

Options:
A. Statistical mean
B. Average area
C. Sum of the weight
D. Volume average value
E. Median length
F. Total volume
G. Total circumference
H. Maximum capacity
I. Half of the maximum value
J. Minimum radius
Answer: B
In engineering, what is the main basis for determining the structure of the pulley?

Options:
A. Bearing load.
B. Cable length.
C. Chain stiffness.
D. Sleeve thickness.
E. Motor torque.
F. Gear ratio.
G. Shaft width.
H. Frame density.
I. Wheel size.
J. Pulley diameter.
Answer: J
When ordinary flat key connections are working, what is the main failure form of the key?

Options:
A. The shaft of the key is warped and useless
B. The body of the key is cracked and flawed
C. The base of the key is chipped and fragile
D. The side of the key is squeezed and damaged
E. The edge of the key is scraped and weakened
F. The core of the key is nicked and weakened
G. The tip of the key is bent and useless
H. The end of the key is twisted and blunted
I. The teeth of the key are smoothed and ineffectual
J. The head of the key is twisted and broken
Answer: D
What are the components of the steady-state error of the control system?

Options:
A. Feedback inconsistency and input variance
B. Operational shift and balance error
C. Response lag and operational delay
D. Response offset and signal mismatch
E. Control discrepancy and adjustment error
F. Adjustment flaw and reaction error
G. Calibration divergence and operation error
H. Following error and disturbance error
I. Tracking error and system deviation
J. Regulation mismatch and execution error
Answer: H
What does the proportional part of the PID regulator mainly adjust?

Options:
A. The noise in the feedback
B. The gain of the system
C. The precision of the control
D. The velocity of the response
E. The pace of the adjustment
F. The stability of the process
G. The resistance of the circuit
H. The frequency of the output
I. The time lag of the signals
J. The amplitude of the input
Answer: B
Among the following types of cavities, which one is definitely a stable cavity?

Options:
A. Confocal cavity
B. Plane-convex structured cavity
C. Non-symmetric parabolic cavity
D. Convex-aspheric cavity
E. Hyperbolic-confocal cavity
F. Plane-concave cavity
G. Concave-convex cavity
H. Bi-concave spherical cavity
I. Symmetric confocal cavity
J. Asymmetric nonfocal cavity
Answer: I
The wavelength of the world's first laser-the ruby laser-is 694.3 nm. Its frequency is_____.

Options:
A. 432 THz
B. 480 THz
C. 460 THz
D. 390 THz
E. 440 THz
F. 450 THz
G. 300 THz
H. 474 THz
I. 500 THz
J. 410 THz
Answer: A
A code word of A-law PCM is C=11100010, with an input signal dynamic range of ±16V. The polarity of the quantized value corresponding to this code word is positive. It is located in the ___ segment and the ___ level within the quantizer segment. The decoded quantized value of this code word should be __.

Options:
A. 6, 2, 1.56250
B. 7, 3, 1.78125
C. 8, 4, 2.12500
D. 6, 3, 1.93750
E. 8, 3, 1.84375
F. 7, 2, 1.40625
G. 5, 2, 1.46875
H. 5, 3, 1.68750
I. 7, 4, 2.03125
J. 6, 4, 2.25000
Answer: B
What are the five components of a general communication system model?

Options:
A. Origin of message, transmission line, encoder, signal reception, and endpoint of information.
B. Message source, transmission path, encoding unit, receiving unit, and information endpoint.
C. Source of information, channel, encoding device, receiving equipment, and destination point.
D. Data origin, communication line, transmitter, signal processor, and data destination.
E. Source data, cable system, modulation equipment, receiver, and final destination.
F. Original data, communication channel, transmitter, receiving unit, and message destination.
G. Information origin, transmission link, signal converter, reception device, and data endpoint.
H. Data source, transmission channel, conversion device, receiver, and final information point.
I. Source of information, transmission equipment, channel, receiving equipment, and destination of information.
J. Information source, transmission medium, modulation unit, receiver, and endpoint.
Answer: I
In the VSB modulation system, if the signal amplitude $A_{0}$ remains unchanged, and the roll-off factor $\alpha$ is increased by double, by how many times does the transmission bandwidth increase?

Options:
A. The transmission bandwidth decreases by a factor of 0.5.
B. The transmission bandwidth increases by a factor of 4.
C. The transmission bandwidth decreases by a factor of 3.
D. The transmission bandwidth remains unchanged.
E. The transmission bandwidth increases by a factor of 1.5.
F. The transmission bandwidth increases by a factor of 2.
G. The transmission bandwidth increases by a factor of 0.5.
H. The transmission bandwidth decreases by a factor of 2.
I. The transmission bandwidth decreases by a factor of 1.
J. The transmission bandwidth increases by a factor of 3.
Answer: F
The Hilbert transform of $sin(\omega _{t} t + 45°)$ is ___.

Options:
A. $cos(\omega _{t} t + 135°)$
B. $sin(\omega _{t} t - 45°)$
C. $cos(\omega _{t} t - 45°)$
D. $sin(\omega _{t} t - 135°)$
E. $sin(\omega _{t} t + 180°)$
F. $cos(\omega _{t} t - 135°)$
G. $sin(\omega _{t} t + 90°)$
H. $cos(\omega _{t} t + 45°)$
I. $sin(\omega _{t} t + 135°)$
J. $cos(\omega _{t} t - 90°)$
Answer: B
The one-sided power spectral density of the additive Gaussian white noise is 76, and the energy of the input signal is E. The maximum signal-to-noise ratio at the output of the matched filter at a given time is ___.

Options:
A. $3E/n _{0}$
B. $2E/n _{1}$
C. $E/3n _{0}$
D. $4E/n _{0}$
E. $2E/n _{0}$
F. $2n _{0}/E$
G. $2F/n _{0}$
H. $E/n _{0}$
I. $E/2n _{0}$
J. $2E/n _{2}$
Answer: E
If the peak value of the voice signal is 4V, and a standard A-law 13-segment PCM quantizer is used, the codeword for a sample value of -1.001V is ___, while the codeword for a sample value of 0.24V is ___.

Options:
A. 01010101, 10101010
B. 00011101, 11100110
C. 01110011, 11001100
D. 11100100, 00011011
E. 01110000, 11001111
F. 10101010, 01010101
G. 10011100, 00110011
H. 01101101, 11000010
I. 00111000, 11110011
J. 11000011, 01111000
Answer: E
The input signal of the DM encoder is a sine wave. When the sampling frequency is doubled, the quantization signal-to-noise ratio increases by ____dB. When the signal amplitude is halved, the quantization signal-to-noise ratio increases by ____dB.

Options:
A. 9, -3
B. 9, -6
C. 9, -9
D. 9, 3
E. 6, 3
F. 18, -6
G. 3, -6
H. 12, -9
I. 6, -3
J. 15, -6
Answer: B
A baseband signal with a radix of M and a symbol period of T seconds has a transmission rate of ___. If symbols appear with equal probability, then the information contained in one symbol is ____, and the transmission rate is ____.

Options:
A. $1/(2T_{s})(Baud), 1Mb, 1/(2T_{s}) Mb/s$
B. $M/T_{s}(Bits), 1Mb, M/T_{s} Mb/s$
C. $M/T_{s}(Baud), 2Mb, M/T_{s} Mb/s$
D. $1/T_{s}(Bits), 1Mb, 1/T_{s} Mb/s$
E. $1/T_{s}(Hz), 1Mb, 1/T_{s} Mb/s$
F. $M²/T_{s}(Baud), 1Mb, M²/T_{s} Mb/s$
G. $1/(MT_{s})(Baud), 0.5Mb, 0.5/T_{s} Mb/s$
H. $1/T_{s}(Baud), 1Mb, 1/T_{s} Mb/s$
I. $M/T_{s}(Baud), 1Mb, M/T_{s} Mb/s$
J. $M/T_{s}(Bits), 2Mb, 2/T_{s} Mb/s$
Answer: H
Quantitative steps directly affect the magnitude of quantization errors, thereby determining the size of the ().

Options:
A. Compression Artifacts
B. Amplitude Levels
C. Mode noise
D. Sampling Rate
E. Signal Bandwidth
F. Quantitative Noise
G. Frequency Response
H. Data Resolution
I. Phase Jitter
J. White Noise
Answer: F
Generally speaking, the greatest waste of communication capacity (i.e., bandwidth) occurs in ().

Options:
A. ADM
B. PAM
C. SDM
D. WDM
E. CDM
F. TDM
G. FDM
H. OFDM
I. QAM
J. SCM
Answer: G
For transmitting 10 bits of data using Hamming code, the required number of redundant bits is ().

Options:
A. 1
B. 5
C. 8
D. 3
E. 10
F. 9
G. 6
H. 2
I. 7
J. 4
Answer: J
Using a $2$-meter diameter reflecting telescope to focus a laser beam $(λ=600 nm)$ on a specific spot on the Moon, and assuming the Moon is $4 \times 10^{5}$ km away from Earth, what is the diameter of the laser spot on the Moon, ignoring the effects of Earth's atmosphere?

Options:
A. $138.2m$
B. $134.6m$
C. $172.8m$
D. $154.3m$
E. $157.2m$
F. $160.4m$
G. $141.7m$
H. $146.4m$
I. $183.5m$
J. $129.9m$
Answer: H
If blue plane light with a wavelength $λ=488 nm$ emitted from an argon ion laser is perpendicularly incident on a horizontal rectangular aperture in an opaque screen, where the dimensions of the rectangular aperture are $0.75 mm × 0.25 mm$, and the diffraction pattern is observed on a screen located at the focal plane of a positive lens $(f = 2.5 m)$ placed near the rectangular aperture, what are the dimensions of the central bright spot?

Options:
A. $1.36 mm×4.08 mm$
B. $1.75 mm×5.25 nm$
C. $1.25 mm×3.75 mm$
D. $2.46 mm×7.38 mm$
E. $0.82 mm×2.46 mm$
F. $1.50 mm×4.50 mm$
G. $2.50 mm×7.50 mm$
H. $1.63 mm×4.88 mm$
I. $1.00 mm×3.00 mm$
J. $2.00 mm×6.00 mm$
Answer: C
When a soap bubble film is illuminated with green light of wavelength $λ=0.5 nm$ and observed at an angle of $30°$ to the plane of the film, the film appears brightest. Assuming the interference order is the lowest at this angle and given that the refractive index of the soapy water is $1.33$, what wavelength of light should be used to observe the film at its brightest when viewed perpendicularly?

Options:
A. $550nm$
B. $745nm$
C. $605nm$
D. $500nm$
E. $485nm$
F. $430nm$
G. $400nm$
H. $720nm$
I. $300nm$
J. $660nm$
Answer: J
In an $F-P$ interferometer, the reflectance coefficient of the inner surfaces of the two glass plates coated with a metallic film is
$r=0.8944$. What is the value of the finesse, the fringe half-width, and the fringe sharpness?

Options:
A. $90, 0.460 rad, 4.60\pi$
B. $65, 0.420 rad, 4.20\pi$
C. $78, 0.446 rad, 4.46\pi$
D. $85, 0.450 rad, 4.50\pi$
E. $60, 0.430 rad, 4.30\pi$
F. $83, 0.449 rad, 4.0 \pi$
G. $70, 0.410 rad, 4.10\pi$
H. $80, 0.447 rad, 4.47\pi$
I. $75, 0.440 rad, 4.40\pi$
J. $82, 0.448 rad, 4.48\pi$
Answer: H
When observing the phosphor screen of an image tube through an eyepiece, the angular resolution of the human eye for the target is $6′$. If the resolution of the image tube's cathode is $m=30 lp/mm$ and the magnification of the image tube is $β=1.5$, what is the minimum focal length of the eyepiece?

Options:
A. 32.40mm
B. 34.75mm
C. 28.65mm
D. 22.10mm
E. 18.95mm
F. 24.30mm
G. 27.25mm
H. 26.80mm
I. 19.15mm
J. 30.50mm
Answer: C
A blazed grating with 100 lines per millimeter is illuminated by monochromatic parallel light with a wavelength of λ = 600 nm, incident perpendicularly to the grating plane. What should the blaze angle be for the second-order spectrum to be in blaze?

Options:
A. 5.48°
B. 3.44°
C. 6.03°
D. 2.88°
E. 7.22°
F. 4.22°
G. 3.98°
H. 4.76°
I. 2.63°
J. 5.12°
Answer: B
When linearly polarized light undergoes total internal reflection at a glass-air interface, and the vibration direction of the electric vector of the linearly polarized light forms a non-zero or $π/2$ angle with the plane of incidence, given that the refractive index of the glass $n=1.5$, at what angle of incidence will the phase difference between the s-polarized and p-polarized reflected light be equal to $40°$?

Options:
A. 57.23° or 41.85°
B. 61.08° or 42.87°
C. 60.47° or 46.05°
D. 55.90° or 47.02°
E. 58.75° or 49.30°
F. 56.45° or 45.12°
G. 54.32° or 42.19°
H. 59.33° or 47.89°
I. 63.01° or 48.67°
J. 62.11° or 44.56°
Answer: C
Given a system of two thin lenses, where $f_{1} =100mm$ and $f_{2} =−50mm$, and the total length is required to be 0.7 times the focal length of the system, what are the distance between the two lenses and the focal length of the system?

Options:
A. 83.21mm; 171.4mm
B. 88.12mm; 160.3mm
C. 81.62mm; 158.1mm
D. 80.34mm; 155.5mm
E. 86.50mm; 170.9mm
F. 78.40mm; 150.6mm
G. 79.87mm; 147.5mm
H. 75.30mm; 145.2mm
I. 92.55mm; 180.8mm
J. 90.45mm; 165.7mm
Answer: C
A thin lens system is composed of two thin lenses with powers of +6 diopters and −8 diopters, separated by a distance of 30 mm. If the order of the two lenses is reversed, what will be the optical power and the principal point location then?

Options:
A. $\varphi = -0.56D, l_{H}' = -428.6mm, l_{H} = -321.4mm$
B. $\varphi = -0.56D, l_{H}' = -418.6mm, l_{H} = -331.4mm$
C. $\varphi = -0.55D, l_{H}' = -426.6mm, l_{H} = -323.4mm$
D. $\varphi = -0.40D, l_{H}' = -418.6mm, l_{H} = -331.4mm$
E. $\varphi = -0.56D, l_{H}' = -321.4mm, l_{H} = -428.6mm$
F. $\varphi = -0.46D, l_{H}' = -328.6mm, l_{H} = -421.4mm$
G. $\varphi = -0.52D, l_{H}' = -425.6mm, l_{H} = -324.4mm$
H. $\varphi = -0.60D, l_{H}' = -430.6mm, l_{H} = -315.4mm$
I. $\varphi = -0.65D, l_{H}' = -428.6mm, l_{H} = -321.4mm$
J. $\varphi = -0.50D, l_{H}' = -428.6mm, l_{H} = -321.4mm$
Answer: A
The group velocity is the speed of movement of the ___.

Options:
A. random phase angles
B. fluctuating frequency peaks
C. shifting density zones
D. unstable wavelength loops
E. harmonious vibratory entities
F. periodic rotation segments
G. irregular motion particles
H. neutral energy waves
I. constant amplitude points
J. adjustable wavelength sections
Answer: I
When a straight rectangular bar is subject to torsion, the correct conclusion is which one?

Options:
A. Torsion does not affect the bar's shape.
B. Warping occurs after the cross-section is deformed.
C. The bar shortens longitudinally under torsion.
D. Torsion causes axial elongation of the bar.
E. The bar experiences no internal stresses.
F. Shear stress is uniform across the section.
G. Torsion results in uniform temperature rise.
H. The material undergoes volume expansion.
I. The bar's density increases with torsion.
J. The cross-section remains perfectly flat.
Answer: B
How many times is the mean square end-to-end distance of a PE free rotating chain larger than that of a free combined chain?

Options:
A. 4
B. 6
C. 1
D. 2
E. 8
F. 3
G. 5
H. 9
I. 7
J. 10
Answer: D
Among the following polymers, which one exhibits optical isomerism and geometric isomerism?

Options:
A. Polypropylene
B. Polybutadiene
C. Polyacrylonitrile
D. Polymethyl methacrylate
E. Polyethylene
F. Polycarbonate
G. Polyvinyl chloride
H. Polytetrafluoroethylene
I. Polystyrene
J. Polyethylene terephthalate
Answer: A
What five characteristics should the test data have?

Options:
A. Precision, variability, representativeness, consistency, completeness.
B. Accuracy, precision, relevance, comparability, variability.
C. Precision, accuracy, relevance, variability, completeness.
D. Accuracy, consistency, representativeness, ambiguity, completeness.
E. Precision, accuracy, representativeness, variability, precision.
F. Precision, ambiguity, relevance, comparability, completeness.
G. Precision, accuracy, representativeness, relevance, variability.
H. Accuracy, variability, consistency, comparability, completeness.
I. Precision, accuracy, representativeness, comparability, completeness.
J. Consistency, accuracy, representativeness, comparability, precision.
Answer: I
What is eutectic transformation?

Options:
A. A reaction where two liquid phases combine to form a stable, singular solid phase.
B. The transformation where several solid forms emerge from differing liquid phases simultaneously.
C. It involves one liquid phase changing directly into two separate solid forms.
D. The process in which two different solid phases crystallize from the same liquid phase is called eutectic transformation.
E. The conversion in which two unique solid formations solidify emerged from the same fluid phase.
F. A phenomenon where multiple liquid phases transform into a single solid phase occurs is known as eutectic transformation.
G. The phase change in which liquid turns into two different solid states simultaneously.
H. A phase shift in which two distinct liquids merge into one solid state.
I. Eutectic transformation refers to when one solid phase splits into two different liquid phases.
J. An occurrence where two separate solid states condense from distinct liquid phases.
Answer: D
What is the assumption underlying the Langmuir adsorption isotherm?

Options:
A. The surface adsorption is always uniform.
B. The heat of adsorption is a constant.
C. The adsorption energy remains variable.
D. The pressure of adsorption is inconsistent.
E. The adsorption energy increases with coverage.
F. The adsorption sites exhibit variability.
G. The number of adsorption sites changes.
H. The temperature of adsorption varies widely.
I. The surface uniformity decreases over time.
J. The coverage of adsorption fluctuates.
Answer: B
What is the reason for the sun producing bright red or orange-yellow hues during sunrise and sunset?

Options:
A. Blue and green light waves have shorter wavelengths and their scattering effects are significant.
B. Blue and green light waves have shorter wavelengths and their transmission effects are significant.
C. Red and yellow light waves have shorter wavelengths and their scattering effects are significant.
D. Blue and green light waves have longer wavelengths and their scattering effects are minimal.
E. Red and yellow light waves have longer wavelengths and their transmission effects are significant.
F. Blue and green light waves have shorter wavelengths and their absorption effects are minimal.
G. Red and yellow light waves have shorter wavelengths and their transmission effects are significant.
H. Blue and green light waves have longer wavelengths and their transmission effects are significant.
I. Blue and green light waves have longer wavelengths and their absorption effects are minimal.
J. Red and yellow light waves have shorter wavelengths and their reflection effects are significant.
Answer: E
The element that causes steel to become thermally brittle is ____.

Options:
A. helium
B. oxygen
C. nitrogen
D. argon
E. carbon
F. sodium
G. iron
H. silver
I. sulfur
J. hydrogen
Answer: I
When replacing the air ventlets and reducing the air pressure during the air break, the first operation is ___.

Options:
A. Clean Filter Cases
B. Install New Air Filters
C. Tighten Radiator Valves
D. Loose Duct Tie Rods
E. Replace Insulation
F. Secure Exhaust Fans
G. Check Coil Connectors
H. Adjust Fan Speed
I. Inspect Compressor Blades
J. Unseal Heater Outlets
Answer: D
The slag alkalinity control value for ordinary steelmaking pig iron produced in blast furnace is ___.

Options:
A. below 0.5
B. just over 2.8
C. around 1.0
D. over 3.0
E. approximately 1.5
F. roughly 0.8
G. close to 2.0
H. nearly 3.5
I. almost 0.3
J. nearly 2.5
Answer: C
The factors affecting the reduction of oxides in slag are ( ), ( ), ( ) and the activity coefficient of element A in metal phase.

Options:
A. ambient temperature, viscosity of slag, concentration of O2.
B. flux temperature, chemical state, concentration of CO.
C. pressure, alloy composition, oxygen solubility.
D. phases present, melting point, CO pressure
E. temperature, slag composition, gas phase CO pressure.
F. heat flux, chemical composition, CO2 partial pressure.
G. carbon content, alloying elements, partial pressure of O2.
H. pressure, metal composition, oxygen concentration.
I. ambient heat, solubility in slag, CO gas pressure.
J. melting point, slag viscosity, gas phase CO2 concentration.
Answer: E
When the oxygen potential in the slag is greater than the oxygen potential in the metal liquid, what is the nature of the slag?

Options:
A. Balanced slag
B. Dry slag
C. Oxidizing slag
D. Neutral slag
E. Reducing slag
F. Wet slag
G. Basic slag
H. Acidic slag
I. Saturated slag
J. Reactive slag
Answer: C
Because the slope of the AfG*-T line of each oxide is different, the two lines often intersect, and the intersection temperature is the reaction ( ).

Options:
A. adjustment temperature
B. conversion temperature
C. reaction rate temperature
D. activation temperature
E. crystallization temperature
F. fusion temperature
G. formation temperature
H. transformation temperature
I. combination temperature
J. equilibrium temperature
Answer: H
( ) is the product of copper sulfide smelting, mainly composed of CU2S and FeS.

Options:
A. Iron matte
B. Copper sulfide
C. Iron sulfide
D. Copper matte
E. Copper oxide
F. Copper carbonate
G. Iron oxide
H. Copper slag
Answer: D
The removal rate in a metallic element is the ratio of ( ) to ( ) of the element.

Options:
A. extraction volume, beginning volume
B. removal percentage, initial percentage
C. reduction degree, base degree
D. decrease rate, primary rate
E. absorption capacity, starting capacity
F. absorption degree, initial degree
G. decay rate, initial quantity
H. reduction rate, total density
I. removal amount, initial amount
J. decrease speed, original mass
Answer: I
What is the reason that high-pressure operation reduces the pressure difference inside the furnace?

Options:
A. Temperature regulation is moderate
B. The control of airflow is enhanced
C. Furnace pressure increases uniformly
D. The distribution of gas is reasonable
E. Combustible materials decrease
F. Air pressure reduction
G. Gas volume reduction
H. Metal melting is significantly increased
I. Smelting efficiency reduces slightly
J. Smelting intensity is relatively low
Answer: G
What is the binding agent in water cannon mud?

Options:
A. Salt and mineral crystals
B. Fireclay
C. Sand and gravel mixture
D. Ash and ceramic particles
E. Charcoal powder
F. Oil and antirust oil
G. Cement and limestone
H. Grass and peat moss
I. Water
J. Organic glue and resin
Answer: I
An increase in certain components in slag can improve the fluidity of the slag. Which components are they?

Options:
A. SiO₂,Fe₂O₃,TiO₂
B. MgO,MnO,FeO
C. MgO,MnO,SiO₂
D. Al₂O₃,MnO,Fe₂O₃
E. MnO,CaO,ZnO
F. FeO,Al₂O₃,CaO
G. SiO₂,FeO,CaO
H. MgO,TiO₂,ZnO
I. Al₂O₃,TiO₂,CaO
J. ZnO,MgO,SiO₂
Answer: B
After the turbulent boundary layer appears, the thermal resistance of convective heat transfer mainly occurs at (), and the thicker () is, the stronger the convective heat transfer is.

Options:
A. Turbulent boundary layer, thick
B. Turbulent flow midsection, thick
C. Turbulent flow edge, thin
D. Laminar flow bottom, thick
E. Turbulent layer top, thin
F. Laminar flow bottom, thin
G. Laminar flow top, thin
H. Laminar flow middle, thin
I. Turbulent boundary center, thin
J. Laminar flow side, thin
Answer: F
Condensation has two forms of bead condensation and film condensation, of which () has a larger heat transfer intensity than () heat transfer, and () is commonly used in engineering.

Options:
A. Heat transfer, bead condensation, film condensation
B. Film condensation, heat transfer, bead condensation
C. Film condensation, bead condensation, heat transfer
D. Bead condensation, heat transfer, film condensation
E. Film condensation, bead condensation, bead condensation
F. Film condensation, film condensation, heat transfer
G. Bead condensation, film condensation, film condensation
H. Bead condensation, heat transfer, bead condensation
I. Heat transfer, film condensation, bead condensation
J. Bead condensation, bead condensation, heat transfer
Answer: G
What is the ratio of the actual heat dissipation of the fin to the heat dissipation assuming that the entire surface of the fin is at the rib base temperature?

Options:
A. Tertiary performance
B. Auxiliary efficiency
C. Secondary productivity
D. Main proficiency
E. Primary efficacy
F. Primary output
G. Auxiliary productivity
H. Tertiary efficiency
I. Main effectiveness
J. Secondary effectiveness
Answer: B
() refers to the heat exchange equipment in which the cold and hot fluids are separated by a solid wall and flow on one side respectively, and the heat is transferred from the hot fluid to the cold fluid through the solid wall.

Options:
A. Membrane heat exchanger
B. Stack heat exchanger
C. Tube heat exchanger
D. Partition heat exchanger
E. Core heat exchanger
F. Barrier heat exchanger
G. Wall heat exchanger
H. Pipe heat exchanger
I. Panel heat exchanger
J. Plate heat exchanger
Answer: G
Natural convection self-modulates under (), when the surface heat transfer coefficient is independent of ().

Options:
A. Gradients, boundary condition.
B. Density, surface area.
C. Temperature, area range.
D. Momentum, design scale.
E. Velocity, material aspect.
F. Altitude, control limit.
G. Humidity, thermal property.
H. Pressure, focal point.
I. Elevation, property factor.
J. Turbulence, feature length.
Answer: J
The blackness of the gray body is independent of ().

Options:
A. Surface roughness
B. Wavelength
C. Temperature
D. Mass
E. Time duration
F. Density
G. Volume
H. Intensity
I. Reflection angle
J. Altitude
Answer: B