7. They had no idea which picture was better, this one or that one?

6. He still remembers when this used to be a quiet village.

5. The question is who will take the place of the manager when he is away.

4. Has it been made public when/how they will come?

3. The police wondered why he killed his own brother so cruelly.

2. I always think of how I can improve my spoken English.

what, which, who, whom, whose, when, where, why, how

1. What surprised us was that the killer was only a boy of 15.

15. Farmers in China began to use tractors to ______ cattle for farming work.

A. replace　　　　　　　 B. take place of

C. in place of　　　　 D. take the place

[解析]选A。replace=take the place of. . . “代替……”。而in place of 是介词短语，此处应用不定式。take place 发生。

14. Scientists disagree about how the universe (宇宙) was______ .

A. invented　　　　　　 B. made

C. discovered　　　　 D. created

[解析]选D。句意：科学家们对宇宙是怎样形成的有分歧。create “创造，形成”；invent “发明”；make “制造”；discover “发现”。