2. 主语从句 在一个句子中做主语成分的从 句叫主语从句。 A. How the book will sell depends on its author. B. That he is the best student in the class is obvious.

3. 主语从句常用 it 作形式主语放句首 因而我们常见到这种句式： It+be+n./adj/-ed 从句（ that, whether,etc.) 例 : It's a pity that you should have to leave. It is great that I have a teacher like you.

4. whether 与 if 均为 “ 是否 ” 但下列情况下只用 whether ： 1. whether 引导主语从句并在句首 Whether he will come is not clear. 2. 引导表语从句 The question is whether he’ll come.

5. 3. whether 从句作介词宾语 I’m not sure about whether we’ll win. 4. 从句后有 "or not" Whether you like it or not, you’ll have to do it.

6. 连接词 1. that That the earth moves around the sun is well known. 2. whether Whether he will come or not is not known yet. 3. who Who will be sent there has not been decided.

7. 4. What What you need is more practice. 5 Which Which one is the best is not clear. 6 When, where Where he has gone is a question.

8. 7 why, how Why there is gravity is hard to understand. How he can earn a living in Britain became a big problem.

9. 8.whoever 、 whatever 、 whichever 可引 导主语从句。 Whoever comes will be welcome. Whatever he did was right. Whichever of you comes in will receive a prize.

10. 主语从句可以放在前面也可 以放在后面。 用 it 作形式主语, 把主语从句 放在句末。

11. 1)It + be + 表语 + 主语从句 It is still uncertain whether he is coming or not. It is strange that they don’t know the film star.

12. 2) It + 不及物动词 + 主语从句 It happens that they were absent. It doesn’t matter whether he will come or not.

13. 3)It + be +done + 主语从句 It has been decided that the park will not be open on Mondays.

14. Attention 1. 主语从句位于句首时必须由连接 词引导。 2. 主语从句位于句末时引导词 that 可省略。 3. 主语从句位于句首时, 不能用 if 引导。 4. 主语从句位于句末时, 可以用 if 引导。

15. 1. ____makes this shop different is that it offers more personal services. A What B Who C Whatever D Whoever

16. 2These wild flowers are so special I would do____ I can to save them. A whatever B that C which D whichever

17. 3 ____in the regulations that you should not tell people the passport of your e-mail account. A What it required B What requires C It is required D It requires

18. 1. It is pretty well understood _____ controls the flow of carbon dioxide in and out the atmosphere today. （ 2003 上海） A. that B. when C. what D. how

19. 2. _____ made the school proud was ____ more than 90% of the students had been admitted to key universities. （ 2003 上海春） A. What; because B. What; that C. That; what D. That; because

20. 3. ______ he referred to in his article was unknown to the general reader. （ 2007 上海） A. That B. What C. Whether D. Where

21. 4. parents say and do has a life-long effect on their children. （ 2007 陕西） A. That B. Which C. What D. As