题目内容：

    Bats(蝙蝠) are the only flying “mammal” in the world. They can't see very well. “As blind as a bat” is often heard. Yet they have no trouble flying on the darkest nights and finding their way round very well. How can bats fly and see at night? They fly by radar(雷达).

The bat's radar system(系统) works the same way as the radar in ships and planes. As a bat flies through the air, it makes a sound. If the sounds hit things, they will come back and the bat's ears will receive the message. In this way, the bat is able to know where the things are.

Bats go out for food at night. In the daytime, they hang in some dark places. Some people regard bats as bad animals. In fact, they are useful animals.

1.As a bat flies through the air, it                .

A.hits things B.comes back C.makes a sound D.carries a machine

2.Bats have no trouble flying on the darkest nights because they        .

A.have very good eyes B.fly with the help of a radar system

C.can easily find food D.live in the darkness

3.Bats are           .

A.friendly to people B.useful for people C.terrible D.dangerous to people

4.Bats can       very well.

A.hear B.see C.run D.jump

5.The passage is about                .

A.a kind of bird B.the radar system

C.animals and human beings D.a kind of animal, the bat