Do you know why different animals or pests have their special colours? Colours in them seem to be used mainly to protect themselves.
Some birds like eating locusts. 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 the harvest time 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 for lives and appear only at night.
If you study the animal life, you'll find the main use of colouring is protecting themselves. Bears, lions and other animals move quietly through forests. They cannot be seen by hunters. This is because they have the colours much like the tree.
Have you ever noticed an even more strange act? A kind of fish in the sea can send out a kind of very black liquid when it faces danger. While the liquid spread over, the enemies cannot find it. And it immediately swims away. So it has lived up to now though it isn't strong at all.
From the passage we learn that locusts ___ .

A．are small animals

B．are easily found by birds

C．are dangerous to their enemies

D．change their colours to protect themselves

How can pests with different colours from plants keep out of danger?

A．They run away quickly.

B．They colours much like their enemies.

C．They hide themselves in the day and appear at night.

D．They have to move quietly.

Bears and lions can keep safe because they ___ .

A．have the colours much like the trees	B．move quickly
C．like brown and grey colours	D．live in forests

Which is the best title for this passage?

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