主语从句& 表语从句
【观察】观察下列句子中从句的用法，然后加以总结。
1. What we need is more time while what they need are more people.
2. It was not known whether/if he would come to the party.
3. Whether we will go fishing tomorrow depends on the weather.
4. Do you think it is necessary that we (should) have all the chairs replaced?
5. It is suggested that you (should) attend the opening ceremony.
6. The question remains whether they will be able to help us.
7. My suggestion is (that) you (should) discuss your problems with your parents first.
8. The reason why I was late this morning is that I missed the early bus.
9. He was very busy. That was why he didn’t come here.
10. Tom looked sad. That’s because he didn’t pass the exam.
11. The house smells as if it hasn’t been lived in for ye ars.
12. Dressed in red, she looks as if she were ten years younger.
13. Has it been decided when we’ll have the final examination?
【总结】
主语从句和表语从句都属于名词性从句。主语从句在复合句中作主语，表语从句在复合句中作表语。在具体的应用中要掌握以下几点：
● 引导词(详见P138-139, B7)
注意易错引导词：
(1) 引导主语从句位于句首时只能用whether (如例句3)，句中可用if (如例句2)，引导表语从句只能用whether (如例句6)；
(2) 主句的主语是reason时，表语从句要用that，不能用because引导(如例句8)；
(3) 引导表语从句时，why强调结果(如例句9)，because强调原因(如例句10)；
(4) that只起连接作用，不在从句中作成分，无词义。引导主语从句时不能省略，引导表语从句时可以省略。
● it作形式主语
有时为避免句子头重脚轻，常用it代替主语从句作形式主语放于句首，而把主语从句置于句末。主句的谓语动词一般用单数形式：
(1) 常用句型：It+be+名词词组/形容词/过去分词+ that从句(如例句4-5)；
(2) 在由连词wh-引导的主语从句中，从句可放在句首，也可用it作形式主语而把从句放在句末(如例句2、
13)。
● 语序：主语从句和表语从句必须用陈述语序。
● 主谓一致
主语从句作主语时谓语动词用单数形式。what引导主语从句，主句的谓语动词多用单数形式，但若表语是复数时，谓语动词用复数形式(如例句1)。
● 语气
(1) 在It is important/strange/natural/necessa ry/essential that…及It
is/was suggested/proposed/ordered/requested/recommended/advised that…从句中需用虚拟语气，动词形式为“(should)+动词原形”(如例句4-5)；
(2) 当主语为suggestion, order, proposal, request, desire, demand等词时，后接表语从句，表语从句中的谓语动词常用“(should)+动词原形” (如例句7)；
(3) 在as if/though引导的表语从句中，谓语动词可用陈述语气(如例句11)，也可用虚拟语气(如例句12)。【高考链接】
1. _______ Barbara Jones offers to her fans is honesty and happiness. (2011 北京)
A. Which
B. What
C. That
D. Whom
2. It is still under discussion _______ the old bus station should be replaced with a modern hotel or not.
(2011 重庆)
A. whether
B. when
C. which
D. where
3. I’d like to start my own business —that’s _______ I’d do if I had the money. (2011 陕西)
A. why
B. when
C. which
D. what
4. I’m afraid he’s more of a talker than a doer, which is _______ he never finishes anything.
(2011 山东)
A. that
B. when
C. where
D. why
5. It was never clear _______ the man hadn’t reported the accident sooner. (2011 江苏)
A. that
B. how
C. when
D. why
【小试牛刀】完成句子（每空一词）。
1. 他学过英语是肯定的。
______ ______ ______ ______ before is certain.
2. 听起来好像有人在敲门。
______ ______ ______ ______ someone is knocking at the door.
3. 你所在的任何地方就是我的家——我唯一的家。
______ ______ ______ is my home — my only home.
4. 还不知道哪个队将赢得这场比赛。
______ ______ ______ ______ ______ ______ ______ ______ the match.
5. 谁将被派去执行这项任务决定了吗？
______ ______ ______ ______ ______ will be sent to carry out the task?
6. 玛丽不再是从前那样了，她活泼开朗。
Mary is no longer ______ she used to be, lively and outgoing.
7. 我听说汤姆去北京了。我想知道他是何时离开的。
I hear that Tom has gone to Beijing. ______ ______ ______ ______ ______ ______ ______.
8. 我的建议是我们明天一早就出发。
My suggestion is ______ ______ ______ ______ early tomorrow.
9. 要求每一位学生按时到校。
