The daytimequalityof light in forests varies with thedensityof thevegetation, theangleof the Sun, and theamountof cloud in the sky. Both animals and plants have different appearances in these various lighting conditions. A color orpatternthat isrelativelyindistinct in one kind of light may be quiteconspicuousin another.

In thevariedandconstantlychanging light environment of the forest, an animal must be able to sendvisualsignals to members of its ownspeciesand at the same timeavoidbeing detected by predators. An animal canhidefrom predators by choosing the light environment in which itspatternisleastvisible. This mayrequiremoving to different parts of the forest at different times of the day or under different weather conditions, or it may be achieved by changing color according to the changing light conditions. Manyspeciesof amphibians (frogs and toads) and reptiles (lizards and snakes) are able to change their color patterns tocamouflagethemselves. Some alsosignalby changing color. Thechameleonlizardhas the moststrikingabilityto do this. Somechameleonspeciescan change from a ratherdullappearanceto a full riot ofcarnivalcolors in seconds. By this means, theysignaltheirlevelofaggressionor readiness tomate.

Otherspeciestake intoaccountthe changing conditions of light by performing theirvisualdisplays only when the light isfavorable. Amalebird of paradise may put himself in the limelight by displaying hisspectacularplumagein the beststagesettingtoattractafemale. Certain butterflies move into spots of sunlight that have penetrated to the forest floor anddisplayby opening and closing their beautifully patterned wings in the bright spotlights They alsocompetewith each other for the bestspotof sunlight.

Very little light filtersthroughthecanopyof leaves and branches in a rain forest toreachgroundlevel—or close to the ground—and at those levels the yellow-to-green wavelengthspredominate. Asignalmight be most easily seen if it is maximally bright. In the green-to yellow lighting conditions of the lowest levels of the forest, yellow and green would be the brightest colors, but when an animal is signaling, these colors would not be veryvisibleif the animal was sitting in an area with a yellowish or greenish background. The bestsignaldepends not only on its brightness but also on how well it contrasts with the background against which it must be seen. In this part of the rain forest,therefore, red and orange are the best colors for signaling, and they are the colors used in signals by the ground-walking Australianbrushturkey. Thisspecies, which lives in the rain forests and scrublands of the eastcoastof Australia, has a brown to-blackplumagewithbare, bright-red skin on the head and neck and a neckcollarof orange-yellow loosely hanging skin. Duringcourtshipandaggressivedisplays, theturkeyenlarges its colored neckcollarby inflating sacs in the neckregionand then flings about a pendulous part of the colored signalingapparatusas it utters calls designed toattractorrepel. Thisimpressivedisplayis clearlyvisiblein the lightspectrumilluminating the forest floor.

Less colorful birds and animals thatinhabitthe rain foresttendtorelyon forms of signaling other than thevisual, particularly over long distances.The piercing cries of therhinoceroshornbillcharacterizethe Southeast Asian rain forest, as do theunmistakablecalls of the gibbons.In densely wooded environments,soundis the best means of communication over distance because incomparisonwith light, it travels with little impediment from trees and othervegetation.In forests,visualsignals can be seen only at short distances, where they are not obstructed by trees.Themaleriflebird exploits both of these modes of signaling simultaneously

in hiscourtshipdisplay.The sounds made as each wing is opened carry extremely well over distance andadvertisehis presence widely.The ritualizedvisualdisplaycommunicates in close

quarters when afemalehas approached. The piercing cries of therhinoceroshornbillcharacterizethe Southeast Asian rain forest, as do theunmistakablecalls of the gibbons. In densely wooded environments,soundis the best means of communication over distance because incomparisonwith light, it travels with little impediment from trees and othervegetation. In forests,visualsignals can be seen only at short distances, where they are not obstructed by trees. Themaleriflebird exploits both of these modes of signaling simultaneously

in hiscourtshipdisplay. The sounds made as each wing is opened carry extremely well over distance andadvertisehis presence widely. The ritualizedvisualdisplaycommunicates in close

quarters when afemalehas approached.

Questions:
question_stem: The phrase conspicuous in the passage is closest in meaning to
choices: tag: A
text: Common

tag: B
text: Noticeable

tag: C
text: Different

tag: D
text: Colorful
answer_key: B
explanation: B conspicuous: 明显的，显而易见的。A 是通常的，普遍的；B 是所以 B 显而易见的，显著的；C 是不同的；D 是富有色彩的，有趣的。所以 B 的 noticeable 正确。

question_stem: According to paragraph 2, what is problematic about an animal's sending visual signals to members of its own species?
choices: tag: A
text: Signs that make an animal visible to its species also make it visible to predators.

tag: B
text: An animal that changes color to avoid predators can confuse members of its species.

tag: C
text: Changing light may require an animal to move beyond the visual range of other members.

tag: D
text: The animal may mistakenly signal aggression when it meant to signal readiness to mate.
answer_key: A
explanation: A 以 members of its own species 做关键词定位至第一句，说动物给自己的同类发信号的时候必须同时避免被天敌看到，所以答案是 A，动物的信号也会被捕食者看到。B 的 change colours，C 的 beyond the visual range 和 D 的 signal aggression 原文都没说。

question_stem: The word signal in the passage is closest in meaning to
choices: tag: A
text: change

tag: B
text: imitate

tag: C
text: communicate

tag: D
text: hide
answer_key: C
explanation: C, signal: verb. 发信号，用信号通知（本意是信号，这是名词的意思，文章中是个动词，而动词的意思必然和名词意思有联系）。A 是改变；B 是模仿；C 是联系，沟通；D 是隐藏。所以答案是 C 的 communicate。

question_stem: According to paragraph 2, all of the following are reasons amphibians and reptiles change color EXCEPT
choices: tag: A
text: changing seasons

tag: B
text: to signal others of their species

tag: C
text: to match the light

tag: D
text: to hide from predators
answer_key: A
explanation: A EXCEPT 题，排除法，A 在原文没有对应点，所以 A 错，选；B 的 signal others 做关键词定位至倒数第三句，正确，不选；C 的 light 做关键词定位至第一句，说光线不断变化，所以 C 正确，不选；D 的 hide from predators 做关键词定位至倒数第四句，说 camouflage themselves，所以 D 正确，不选。

question_stem: According to paragraph 3, butterflies move into spots of sunlight in order to
choices: tag: A
text: warm their wings in order to open them

tag: B
text: compete with each other

tag: C
text: take advantage of favorable light conditions on the forest floor

tag: D
text: imitate birds of paradise
answer_key: C
explanation: C 以 butterfly 做关键词定位至第三句，说蝴蝶 move into 并且 display blabla，但这句话没说为什么蝴蝶要 move，最后一句非常清楚地说蝴蝶会彼此竞争最好的阳光，也就是 C 说的利用光线条件，所以答案是 C，B 虽然说了 compete，但没说 compete 什么，所以不对，其他的都是单纯说事件没说原因，所以不对。

question_stem: According to paragraph 4, what is true about light that reaches ground level?
choices: tag: A
text: It reveals only the yellow and green colors animals use to signal each other.

tag: B
text: It reflects the yellow and green colors to make the floor as bright as sunshine.

tag: C
text: It camouflages animals whose natural colors are yellow and green.

tag: D
text: It consists mostly of yellow-to-green wavelengths.
answer_key: D
explanation: D 以 light that reaches ground level 做关键词定位至第一句，说到达地面的光以黄绿波长的为主，D 是原文的忠实改写，其他都没说，关键词定准后只读一句话就可以又快又好拿出答案。

question_stem: Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
choices: tag: A
text: When an animal is signaling in an area with green-to yellow lighting condition. It’s signal will not be visible if the background is brightly lit.

tag: B
text: In the lowest levels of the forest, an animal's signals are not easily seen unless there is a yellowish or greenish background.

tag: C
text: In the green-to-yellow lighting conditions at the lowest levels of the forest, only signals that are themselves green or yellow will be bright enough to be seen in most areas.

tag: D
text: Although green and yellow would be the brightest colors near the forest floor, these colors would make poor signals whenever the forest background was also in the green-to-yellow range.
answer_key: D
explanation: D 原句的主要逻辑是转折，主干是：本来 yellow 和 green 最亮，但如果背景也是黄绿色就不亮了。D 正确，将主要的内容和逻辑都重现了出来。A 的 brightly lit 原文没说；B 与原文说反；C 的 only 不对，而且 most areas 原文也没说。

question_stem: The word inflating in the passage is closest in meaning to
choices: tag: A
text: Coloring

tag: B
text: Enlarging

tag: C
text: Loosening

tag: D
text: Heating
answer_key: B
explanation: B inflate: 是膨胀，充气。A 是粉饰，使…变色；B 是扩大；C 是放松；D 是加热。所以 B 的 enlarging 是答案。

question_stem: Which of the following can be inferred from paragraph 4 about yellow and green colors compared with red and orange colors at the bottom of the forest?
choices: tag: A
text: Yellow and green are better colors for signaling than red and orange colors.

tag: B
text: Orange and red are brighter colors than yellow and green.

tag: C
text: Yellow and green are likely to be more common in the background than red and orange.

tag: D
text: Orange and red colors do not contrast as well with the forest floor as yellow and green do.
answer_key: C
explanation: C 以 red and orange colours 做关键词定位至第五句，说在靠近地面的森林里，红色和橙色是最好的信号色，与之对照，黄色和绿色是除了靠近地面的部分之外其他部分最好的信号颜色，也就是答案 C 说的黄绿色比红橙色更多用于信号。A 不全面，如果在靠近地表的地方，黄绿色就不好；B 和 D 与原文说反。

question_stem: What can be inferred from paragraph 5 about the less colorful birds and animals that inhabit the forest?
choices: tag: A
text: These species are less able to see color. and therefore they communicate with one another using nonvisual signals.

tag: B
text: These species generally live in less densely wooded environments than more colorful birds and animals do.

tag: C
text: The cries of these species do not carry as well over distances as the cries of more colorful birds and animals.

tag: D
text: These species depend more on nonvisual signals for communication because they are less visible in their environment.
answer_key: D
explanation: D 以 less colourful birds and animals 做关键词定位至第一句，原句说这些动物会更多依靠非视觉的信号来交流，答案是 D。B 和 C 没说，A 说他们依靠非视觉，而原文说更多依靠非视觉，是不一样的，而且原文也没说这些动物看不见颜色，所以 A 错。

question_stem: The word impediment in the passage is closest in meaning to
choices: tag: A
text: obstruction

tag: B
text: effort

tag: C
text: delay

tag: D
text: resistance
answer_key: A
explanation: A impediment: 障碍，阻碍。A 是阻碍；B 是努力；C 是延迟；D 是阻力，电阻，抵抗。所以 A 的 obstruction 正确。

question_stem: The word exploits in the passage is closest in meaning to
choices: tag: A
text: repeats

tag: B
text: makes use of

tag: C
text: increases the intensity of

tag: D
text: recognizes
answer_key: B
explanation: B，exploit: 利用，开采，开发，剥削。A 是重复；B 是利用；C 是增加强度；D 是认出。 所以 make use of 正确。