题干
Do you know why different animals or pests（昆虫）have their special colours？ Colours in them seem to be used mainly to protect themselves.
Some birds like eating locusts（蝗虫）,but birds cannot easily catch them.
Why？It is because locusts change their colours together with the change of the colours of crops. When crops are green,locusts look green. But as autumn comes,locusts change to the same brown colour as crops have. Some other pests with different colours from plants are easily found and eaten by others. So they have to hide themselves in the day and appear only at night.
If you study the animal life,you'll find the main use of colours is protecting themselves. Bears,lions and other animals move quietly through forests. They cannot be easily seen by hunters. This is because they have the colours much like the trees.
Did you ever notice even strange act？A kind of fish in the sea can send out a kind of very black liquid（液体）when it faces danger. While the liquid comes out,other sea animals cannot find it. So it can easily swim away. It's not strong at all. But in this way it has lived up to now.
【小题1】From the passage we learn that locusts.| A．can change their colours only in autumn | B．are easily found by birds |
| C．are dangerous to the birds | D．can change their colours to protect themselves |
| A．They have the colours much like their enemies. | B．They run away quickly. |
| C．They hide themselves in the day and appear only at night. | D．They have to move quietly. |
| A．have the colours much like the things around them | B．move quietly |
| C．like brown and grey colours | D．live in forests |
| A．it is very big and strong | B．the liquid it sends out can kill other fish |
| C．the liquid it sends out helps it run away | D．it swims faster than any other fish |
| A．The Change of Colours for Animals and Pests | B．Colours of Different Animals and pests |
| C．The Main Use of Colours for Animals and Pests | D．Some Animals and Pests |
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