1. B最佳 分析: 该题考查引导定语从句的关系代词的用法。该句的空白之后为一非限制性定语从句，应用关系代词引导，排除C、D。who和which都能引导非限制性定语从句。但who引导的非限制性定语从句用来修饰表示人的先行词；which引导的非限制性定语从句可修饰前面整个句子，并代表主句所表达的内容，故答案选B。又如：Bamboos are hollow, which makes them very light.竹子是空心的，这使它很轻。

12．See the flags on the top of the building！ That was _____we did in the morning. (NMET2006 23)

A. when　 B. which　　 C. where　　 D. what

[点拨]：

11. I have many friends, ______some are businessmen. (NMET2005 24)

A. of them　　　　 B. from which　　　　 C. who of　　　 D of whom

10. Mary wrote an article on _____the team had failed to win the game. (NMET2005 23)

A. why　　　　　 B. what　　　　　 C. who　　　 　　D. that

9. You are saying that everyone should be equal, and this is ______I disagree.

(NMET2004 31)

　 A. why　　　　　 B. where　　　　　 C. what　　　　　 D. how

8. The English play _______ my students acted at the New Year's party was a great success. (NMET2004 23)

　 A. for which　　　　　 B. at which　　　　 C. in which　　　　 D. on which

7. Don't be afraid of asking for help ____ it is needed.　 (NMET2003 21)

　 A. unless　　　　　 B. since　　　　　 C. although　　　　　 D. when

6. John shut everybody out of the kitchen ______ he could prepare his grand surprise for the party. (NMET2002 30)

　 A. which　　　　 B. when　　　　　 C. so that　　　　　 D. as if　　　　

5. The mother didn't know ______ to blame for the broken glass as it happened while she was out. (NMET2002 24)

　 A. who　　　 B. when　　　 C. how　　　 D. what

4. _____ is known to everybody, the moon travels round the earth once every month. (NMET2001 34)

　 A. It　　　　 B. As　　　　 C. That　　　　　 D. What