题目内容：

补全对话

A: Hi, David. 1.       

B: I’m looking for some information about Journey to Mars.

A: Journey to Mars? Do you want to travel to Mars? 2.       

B: No, it’s the name of a book. It’s about space travel.

A: I see. 3.       

B: No, I haven’t. I’m not interested in space travel.

A: But there are too many people on the earth. 4.       

B: So you want to know something about Mars, right?

A: Yes. Have you heard the latest news? A spaceship has traveled to Mars.

B: Yes, I have. 5.        but I’m afraid people can’t live there.

A: Then scientists have to discover some other planets for people to live on.

B: Yes, what can we do now?

A: We should study hard to improve our environment.

B: You’re right.

A. I think it’s impossible for the common people. B. Maybe we have to live on other planets one day. C. But scientists haven’t discovered any life on it. D. What are you doing? E. Have you ever read it before?