阅读理解：
Have you ever wondered why different animals or pests have their
particular(特定的) colors? Colors in them seem to be used mainly to protect
themselves.
Birds, especially seagulls, are very fond of locusts, but birds cannot
easily catch locusts because locusts change their colors together with the
change of the color of crops. When crops are green, locusts look green. But when
crops are ripe, locusts take on exactly the same brown color as crops have. Some
other pests with different colors from plants are usually easily found and eaten
by their enemies. So they have to hide themselves in terror(惊慌地) for lives and
appear only at night.
If you study the animal life in any part of the world, you will find the main use of coloring is to protect themselves. Bears, wolves and other beasts move quietly through forests. They are usually invisible to the eyes of hunters, because they have the color much like the barks of trees.
An even stranger act remains to be noticed. A kind of fish living in seas can send out a kind of very black liquid when it faces danger. While the liquid spreads over, its enemies cannot find it, and it immediately swims away. Thus, it has existed(存活) up to now though it is not powerful at all.
问题：
1.This passage is mainly about .
A.the protective coloration of animals and pests
B.how a certain sea fish protects itself
C.animals or pests can dye themselves different colors
D.the change of color in locusts
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【参考答案】A[考点]主旨大意题【精析】A 文章开篇以问句“Have you ever wondered why different animals or pests have their particular colors?(你是否曾好奇为什么不同的动物或害虫有它们特定的颜色?)”引入主题，第一段第二句“Colors in them seem to be used mainly to protect themselves.”点明了主旨，即动物或害虫身上的颜色似乎主要是用来保护它们自己的，接下来以鸟类、蝗虫、熊和狼等动物为例证明了这一观点。另外，第三段第一句“…the main use of coloring is to protect themselves.”再次呼应主旨。故选A。
2. Locusts are but they are not easily wiped out by their enemies because .
A.beasts; they are dangerous to their enemies
B.pests; they take on the same color as crops
C.birds; they fly extraordinarily fast
D.animals; they are powerful enough
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【参考答案】B[考点]推理判断题【精析】B 根据第二段第一句“…but birds cannot easily catch locusts because locusts change their colors together with the change of the color of crops.”和第四句“Some other pests with different colors…”可知，鸟儿不容易抓到蝗虫，因为蝗虫会随着庄稼的颜色而改变自己的颜色。一些和植物颜色不同的其他害虫通常很容易被敌人发现并吃掉。此处是在对比蝗虫(locusts)与其他和植物颜色不同的害虫，根据常识也可推知蝗虫是一种害虫(pest)。故选B。
3. The pests that have different colors from plants usually appear at night because .
A.they have the habit of coming out in darknessB.it's easy for them to destroy plants in darknessC.birds take their rest when night comesD.their enemies tell them to do so
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【参考答案】C
[考点]推理判断题
【精析】C 根据第二段最后两句“Some other pests with different colors from plants are usually easily found and eaten by their enemies. So they have to hide themselves in terror for lives and appear only at night.”可知，一些和植物颜色不同的害虫通常很容易被敌人发现并吃掉，所以为了生存它们不得不惶恐地藏起来，只在晚上出没。由此可推知，和植物颜色不同的害虫选择在晚上出没的原因是敌人(鸟儿)晚上要休息。故选C。
4. Bears and wolves have the same colors as barks of trees because .
A.they like brown or grey colors
B.they enjoy walking through forests quietly
C.the colors help prevent themselves from being noticed
D.they fear other beasts
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【参考答案】C
[考点]事实细节题
【精析】C 根据第三段最后两句“Bears, wolves and other beasts move quietly through forests. They are usually invisible to the eyes of hunters, because they have the color much like the barks of trees.”可知，熊、狼和其他野兽在森林中安静地移动，猎人的眼睛通常是看不到它们的，因为它们的颜色和树皮十分相似。故选C。
5. The fish mentioned in the last paragraph can survive up till now because .
A.it can run faster than its enemies
B.it can send out black liquid
C.it can change its skin colors
D.it is powerful
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【参考答案】B[考点]推理判断题【精析】B 根据最后一段最后三句“A kind of fish living in seas can send out a kind of very black liquid when it faces danger. While the liquid spreads over…though it is not powerful at all.”可知，一种生活在海洋中的鱼在遇到危险时可以释放出一种很黑的液体，当这