We know that many animals do not stay in one place.Birds,fish and other animals move from one place
题目
We know that many animals do not stay in one 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 others 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 (迁移) is probably the migration of fish,which is called “salmon”.This fish is born in fresh water but it travels many miles to salt water.There it spends its life.When it is old,it returns to its birthplace in fresh water.Then it gives birth and dies.In northern Europe,there is a kind of mouse.They leave their mountain homes when they become 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 (近来),scientists have studied the migration of a kind of lobster
答案
1、C They move for different reasons:most of them move to find food more easily,but others move to get away from places that are too crowded.
2、A This fish is born in fresh water but it travels many miles to salt water.There it spends its life.
3、B They leave their mountain homes when they become too crowded.
4、B Nobody knows why they do this,and nobody knows where they go.
5、D
举一反三
已知函数f(x)=x,g(x)=alnx,a∈R.若曲线y=f(x)与曲线y=g(x)相交,且在交点处有相同的切线,求a的值和该切线方程.
我想写一篇关于奥巴马的演讲的文章,写哪一篇好呢?为什么好
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