We know that many animals do not stay in _______ place.Birds,fish and other animals move from one place to another at a

We know that many animals do not stay in _______ place.Birds,fish and other animals move from one place to another at a certain time.They move for different reasons:most of them move to find food more easily,but some move to get away from places that are too crowded.
When cold weather comes,many birds move to warmer places to find food.Some fishes give birth in warm water and move to cold water to feed.The most famous migration is probably the migration of one kind of fish,which is called “salmon”.This fish is born in fresh water but it travels many miles to salt water.There it spends most of its life.When it is old,it returns to its birthplace in fresh water.Then it gives birth and dies there.In northern Europe,there is a kind of mouse.They leave their mountain home when it becomes too crowded.They move down to the low land.Sometimes they move all the way to the seaside,and many of them are killed when they fall into the sea.
Recently,scientists have studied the migration of a kind of lobster(龙虾).Every year,when the season of the bad weather arrives,the lobsters get into a long line and start to walk across the bottom of the ocean.Nobody knows why they do this,and nobody knows where they go.
So,sometimes we know why humans and animals move from one place to another,but at other times we don’t.Maybe living things just like to travel.
( )1.The main reason why animals move from one place to another is ________.
A.to find food more easily B.that they are afraid of humans
C.that they feel too crowded D.that they don’t like the same place
( )2.The salmon is born in ________ and live in ________ most of the time.
A.warm water; fresh water B.cold water; salt water C.fresh water; salt water D.warm water; cold water
( )3.The underlined word “migration” in the second paragraph means “______” in Chinese.
A.撤退 B.迁徙 C.活动 D.游动
( )4.The lobsters usually move when ________.
A.the place is crowded B.winter comes C.the bad weather arrives D.they give birth
( )5.What’s the main idea of this passage?
A.The migration of some animals.B.Why living things like to travel.
C.Some interesting fishes.D.Some interesting animals