题目内容：

For many years people believed that the cleverest animals after man were chimpanzees. Now, however, there is proof that dolphins may be even cleverer than these big apes.

Although a dolphin lives in the sea, it is not a fish. It is a mammal. It is in many ways, therefore, like a human being（人）．

Dolphins have a simple language. They are able to talk to one another. It may be possible for man to learn how to talk to dolphins. But this will not be easy because dolphins can not hear the kind of sounds man can make. If man wants to talk to dolphins, therefore, he will have to make a third language which both he and the dolphins can understand.

Dolphins are also very friendly towards man. They often follow ships. There are many stories of dolphins guiding ships through difficult and dangerous waters.

1. Which animals do people think may be the cleverest?

A. Dolphins    B. Mammals.   

C. Big apes.    D. Chimpanzees.

2. Why is a third language necessary if man wants to talk to dolphins?

A. The dolphin language is hard to learn.

B. Dolphins cannot hear men speaking.

C. Most men do not speak English.

D. Men want to talk to dolphins in secret.

3. What have scientists discovered about dolphins?

A. Men can now talk to them.

B. They understand a simple language.

C. They can teach men their languages

D. They can speak to one another.

4.In what way are dolphins friendly to man?

A. They often follow ships.   

B. They like interesting things about man.

C. They often jump onto ships   

D. They seem to like stories.