上海被列为36个水质型缺水城市之一，并被联合国预测为21世纪洁净水严重缺乏的世界六大城市之一．造成水质型缺水的主要原因是（　　）

A．河流上游水源污染较严重

B．淡水资源短缺

C．降雨量不均衡

D．取水点远离城市

根据语境，填写适当的词语或句子补全对话。

A: Look at the man running down the street. Why do you think he is running?

B: He could be running for exercise.

A: No.  He might be running to _    1 ___. He is wearing a suit.

B: But there is no bus on this road.  Buses are not       2       to run here.

A: Oh! Maybe he is going to be late and running to work.

B: I don't think so.  He _    3  __ scared.

A: Yes.  You are right.  Look! What's that in the sky?

B: It _    4  __ a UFO.  And it's landing.

A: Look at that woman with a camera.

B: She must be a reporter from the TV news.

A: No.  Look at those other people.  They are actors.  Oh, I see.       5      .