必修三Unit4主语从句

必修三Unit4主语从句(Subject Clause)
➢定义:
在句子中担当主语的是一个从句，这个从句就叫做主语从句。

➢位置：
1.通常放在主句谓语动词之前
That he will succeed is certain. Who will be our monitor hasn't been decided yet.
Whether he will join us won't make difference. How the book will sell depends on its author. What caused the accident remains unknown.
2.由形式主语it代替，而本身放在句子末尾。

It doesn’t matter whether he is wrong or not.
➢辨别下列从句的类别(1-6)：主从；宾从；表从；主从；宾从；主从
➢主语从句的连接词
引导主语从句的连接词可分为三类：连接词：that, whether / if；连接代词：what, which who, whom, whose, whatever, whoever, whichever等；连接副词：when, where, how, why, whenever, wherever等。

●that:1.无词义；2.在主语从句中不作成分；3.一般不能省略（尤其在句首时）
That he will come and help us is certain. That he is the best student in the class is obvious.
●Whether / if: 1.有词义：“是否”；2.在主语从句中不作成分；3. whether引导的主语从句可
放句首、句末；4. If引导的主语从句不能位于句首。

Whether we will succeed is still a question. If we will succeed is still a question. (×)
It is not known whether / if he will come.
what, whatever, who, whoever, whose, which, whichever
when, where，why, how等。

1.有词义；
2.在主语从句中作成分。

What he is has nothing to do with you. Whose ticket this is has not been found out.
When the test will be given is not yet decided. Whatever you did is right.
➢如何选择连接代词和连接副词
在主语从句中，连接词的选择要看这个从句的句子结构，假如根据意思判断为缺少主语，宾语，表语等时应该考虑who, whoever, which, whichever, what, whatever, whom, whomever；如果缺少定语则想到whose, which；如果缺少状语则应该选择how, where, when, why等。

因此要想做好题目首先得了解句子成分。

What I can’t understand is why he has changed his mind.
（缺少understand的宾语，意为“…的事”）
Whoever breaks the law will be punished.（缺少breaks的主语，意为“无论谁”）
➢主语从句后置！
为了避免主语冗长，句子头重脚轻，主语从句作主语时通常用it作形式主语，主语从句放在后面作真正的主语。

That he finished writing the composition in such a short time surprised us.
=It surprised us that he finished writing the composition in such a short time.
Whether he will come or not doe sn’t matter. =It doesn’t matter whether he will come or not. Who will do that job is not yet decided. =It is not yet decided who will do that job.
➢用it作形式主语的that从句有以下搭配关系：
1. It + be +形容词+ that从句
It is necessary / important / obvious / certain / natural…that…
It is necessary that the problem should be discussed at once.
2. It + be +名词+ that从句
It is a pity / a shame / no wonder/ an honour / no surprise…that…
It's a wonder that he didn't fail.
3. It + be + -ed分词+ that从句
It is believed / reported / said/ thought/expected /known that…
It is said that he‘s got married.
4. It +不及物动词+ that分句
It appears/seems /happens/matters/ occurred to that…
It seems that he has seen the film.
➢主语从句的语序和时态
【观察】
Why he did it will remain a puzzle forever. How this happened is not clear to anyone. What you need is more practice. What you need was mentioned by him.
归纳：主语从句的语序用陈述语序；主语从句的时态不受主句的时态影响和限制。

➢主语从句作主语时主句中的谓语动词的单复数情况
How he worked it out is still a secret. Who will write the poem has not been decided yet. How it was done was a mystery. Where she has gone remains not known yet.
What we need is more time. What we need are many more books.
总结：当主语从句作主语时，主句中的谓语动词一般用第三人称单数，但what引导主语从句的主句谓语动词的形式须根据句子的意思来判断或根据主句中的表语来决定。

What they makes in this factory TV sets.
What he’d like most for a birthday present a camera.
It was my suggestion that made him confident of success.
→My suggestion made him confident of success.（句子仍然成立，是强调句）
It was my suggestion that he needs more practice.
→My suggestion he needs more practice.（句子不成立，是主语从句）
➢改错答案：1. shall we →we shall; 2. That you; 3. That →It 4. are →is; 5. If →whether
➢用连接词填空答案：1. that; 2. Whoever; 3. That; 4. Whether; 5. Which
➢用主语从句翻译句子答案
1. Where he lives is a puzzle.
2. It is certain that nothing will prevent us from coming here.
3. That she has just given birth to a healthy baby girl made us excited.
➢选择题答案：1-5: CBACB 6-10: DCDAD。