Problem: Incandescent light bulb:

There are many non-incandescent light sources, such as the fluorescent lamp, high-intensity discharge lamps and LED lamps, which have higher luminous efficiency, and some have been designed to be retrofitted in fixtures for incandescent lights. These devices produce light by luminescence. These lamps produce discrete spectral lines and do not have the broad "tail" of invisible infrared emissions. By careful selection of which electron energy level transitions are used, and fluorescent coatings which modify the spectral distribution, the spectrum emitted can be tuned to mimic the appearance of incandescent sources, or other different color temperatures of white light. Due to the discrete spectral lines rather than a continuous spectrum, the light is not ideal for applications such as photography and cinematography.

How can luminescent light sources be modified to resemble the appearance of incandescents?
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A: By careful selection of which electron energy level transitions are used, and fluorescent coatings which modify the spectral distribution

Problem: The Gospel of Luke begins its account of Mary's life with the Annunciation, when the angel Gabriel appeared to her and announced her divine selection to be the mother of Jesus. According to gospel accounts, Mary was present at the Crucifixion of Jesus and is depicted as a member of the early Christian community in Jerusalem. According to Apocryphal writings, at some time soon after her death, her incorrupt body was assumed directly into Heaven, to be reunited with her soul, and the apostles thereupon found the tomb empty; this is known in Christian teaching as the Assumption.
What did Gabriel announce to Mary at the Annunciation?
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Answer: her divine selection to be the mother of Jesus

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The area receives about 820 millimetres (32.3 in) of annual rainfall, which is concentrated from June through September/October with little or no precipitation the remainder of the year. The area has two main seasons. The rainy season runs from June to October when winds bring in tropical moisture from the sea. The dry season runs from November to May, when the air is relatively drier. This dry season subdivides into a cold period and a warm period. The cold period spans from November to February when polar air masses push down from the north and keep the air fairly dry. The warm period extends from March to May when tropical winds again dominate but do not yet carry enough moisture for rain.
When is it coldest in Mexico City?
A: November to February

Context and question: The abbey was restored to the Benedictines under the Catholic Mary I of England, but they were again ejected under Elizabeth I in 1559. In 1560, Elizabeth re-established Westminster as a "Royal Peculiar" a church of the Church of England responsible directly to the Sovereign, rather than to a diocesan bishop and made it the Collegiate Church of St Peter (that is, a non-cathedral church with an attached chapter of canons, headed by a dean.) The last of Mary's abbots was made the first dean.
Who ejected the Benedictines again in 1595?
Answer: unanswerable

Question: Fused quartz is a glass made from chemically-pure SiO2 (silica). It has excellent thermal shock characteristics, being able to survive immersion in water while red hot. However, its high melting-temperature (1723 C) and viscosity make it difficult to work with. Normally, other substances are added to simplify processing. One is sodium carbonate (Na2CO3, "soda"), which lowers the glass transition temperature. The soda makes the glass water-soluble, which is usually undesirable, so lime (calcium oxide [CaO], generally obtained from limestone), some magnesium oxide (MgO) and aluminium oxide (Al2O3) are added to provide for a better chemical durability. The resulting glass contains about 70 to 74% silica by weight and is called a soda-lime glass. Soda-lime glasses account for about 90% of manufactured glass.
Is there an answer to this question: What causes glass to dissolve in Na2CO3?

Answer: unanswerable

Problem: Egypt:

Muhammad Ali Pasha evolved the military from one that convened under the tradition of the corvee to a great modernised army. He introduced conscription of the male peasantry in 19th century Egypt, and took a novel approach to create his great army, strengthening it with numbers and in skill. Education and training of the new soldiers was not an option; the new concepts were furthermore enforced by isolation. The men were held in barracks to avoid distraction of their growth as a military unit to be reckoned with. The resentment for the military way of life eventually faded from the men and a new ideology took hold, one of nationalism and pride. It was with the help of this newly reborn martial unit that Muhammad Ali imposed his rule over Egypt.

Who modernized Egyptian army?
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A:
Muhammad Ali Pasha