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Different animals or pests have their particular colors. Why?

Particular colors will protect themselves. For example, birds, especially seagulls, are very fond of locusts, but birds can't 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 for lives and appear only at night.

The main use of color is to protect themselves. Bears, wolves and the other beasts move quietly through forests. They are usually invisible to eyes of hunters, because they have the color much like the barks of trees.

An even more strange 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, its enemies cannot find it, and it quickly swims away. Thus, it has existed up to now though it is not powerful.

1.Why aren’t locusts easily found by their enemies?

A Because they fly very fast.

B Because they are powerful enough.

C Because they are dangerous to their enemies.

D Because they take on the same colors as crops.

解析：选D。细节理解题。根据第二段第二句For example, birds, especially seagulls, are very fond of locusts, but birds can't easily catch locusts because locusts change their colors together with the change of the color of crops.可知例如，鸟类，特别是海鸥，非常喜欢蝗虫，但是鸟类很难捕捉蝗虫，因为蝗虫会随着农作物颜色的改变一起改变它们的颜色，故选D。

2.Why do the pests that have different colors from plants usually appear at night?

A Because birds take their rest when night comes.

B Because they have the habit of coming out in darkness.

C Because it's easy for them to destroy plants in darkness.

D Because their enemies can easily find them and eat them.

解析：选D。细节理解题。根据第二段倒数第二句Some other pests with different colors from plants are usually easily found and eaten by their enemies.可知其他的一些害虫，和植物颜色不同，通常很容易被敌人发现和吃掉，故选D。

3.What’s the main use of color?

A To protect themselves.

B To show off themselves.

C To be beautiful and attractive.

D To make themself become the king or queen.

解析：选A。细节理解题。根据第三段第一句The main use of color is to protect themselves.可知颜色的主要用途是保护自己，故选A。

4.Which of the following is the reason why bears and wolves have the same colour as barks of trees?

A They fear other beasts.

B They like brown or gray color.

C The colors help prevent themselves from being noticed.

D They think brown or gray color make them attractive.

解析：选C。细节理解题。根据第三段第三句They are usually invisible to eyes of hunters, because they have the color much like the barks of trees.可知猎人通常发现不了它们，因为它们的颜色很像树皮，故选C。

5.Why isn’t the fish easily found by its enemies?

A Because it swims fast.

B Because it can send out black liquid.

C Because it can hide itself well.

D Because it is very powerful.

解析：选B。B 推理判断题。根据最后一段A kind of fish living in seas can send out a kind of very black liquid. When it faces danger, its enemies cannot find it, and it quickly swims away.可知，这种鱼会释放出一种极黑色液体，这使得它不容易被敌人发现，故选B。