第三部分 阅读理解(共20小题；每小题2分，满分40分)
阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题卡上将该项涂黑。
A.
Have you ever wondered why different animals or pests have their particular colours? Colours 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 colours together with the change of the colour of crops. When crops are green, locusts look green. But when crops are ripe, locusts take on exactly the same brown colour as crops have. Some other pests with different colours 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.
If you study the animal life in any part of the world, you will find the main use of colouring 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 colour 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. While the liquid spreads over, its enemies cannot find it, and it immediately swims away. Thus, it has existed up to now though it is not powerful at all.
56. This passage mainly talks about ________.
A. the change of colour in locusts
B. the protective coloration of animals and pests
C. how a certain sea fish protects itself
D. animals or pests can dye themselves different colours
57. Locusts are ________ but they are not easily wiped out by their enemies because ________.
A. animals; they are powerful enough B. beasts; they are dangerous to their enemies
C. pests; they take on the same colours as crops D. birds; they fly extraordinarily fast
58. The pests that have different colours from plants usually appear at night because ________.
A. their enemies can easily find them and eat them
B. they have the habit of coming out in darkness
C. it’s easy for them to destroy plants in darkness
D. birds take their rest when night comes
59. Bears and wolves have the same colour as barks of trees because ________.
A. they fear other beasts
B. they like brown or grey colours
C. they enjoy walking through forests quietly
D. the colours help prevent themselves from being noticed
