导入：观察并指出句子成分
A tree has fallen across the road. You are a student.
To find your way can be a problem. Smoking is bad for you.
一．概念：
主语：主语是指句子谈论的主题，说明的人或事物。也就是句中动作、行为、性质和状
态的主体，一般位于句首
主语从句：在句中充当主语的从句
二·基本结构
关系词 简单句 谓语动词 宾语 同位语
That he finished writing the composition in such a short time surprised us all. 他在很短的时间内写完作文让我们都很惊讶
三 关系词(引导词)
1． 从属连词：that whether
that 引导主语从句只起引导作用，本身无实际意义，在主语从句中不充当任何成分，但不能省略。
That she left him cut him to the heart. That he will come is certain.
注意：有时为了使句子结构平衡, 避免 “头重脚轻”, 常用 it 作形式主语, 而把从句放在后面。E.g
That she has made such a mistake is a pity. It is a pity that she has made such a mistake. 这样就构成了下面一些常用句型: 1) It is + adj. +从句 It is necessary that… 有必要…
It is important that …. 重要的是… It is obvious that…… 很明显…… 2) It +不及物动词+从句
It seems/appears that... 似乎……
It happened that... 碰巧……
It occurred to me that…… 我突然想起…… 3) It + be +过去分词+从句 It is said that... 据说……
It is known to all that... 众所周知…… It is reported that... 据报道……
It is believed that... 据信……;人们相信…… It is suggested that... 有人建议……
It must be pointed out that... 必须指出…… It has been proved that... 已证明……. 4) It is + n. +从句
It is common knowledge that… …是常识 It is a surprise that …. 令人惊奇的是… It is a fact that…… 事实是……
由whether及其他连词引导的主语从句放在句首，句后都可。 Whether it will please them is hard to say. It is hard to say whether it will please them.
2. 连接代词：who whoever whom whose what whatever which whichever What seems easy to some people seems difficult to others. Which side will win is not clear.
注意：what 与that 在引导主语从句时的区别
what 引导主语从句时在从句中充当句子成分, 如主语、宾语、表语, that 则不充当任何成分无意义。 例如：What you said yesterday is right.
That she is still alive is a consolation 3. 连接副词：when where how why等 Why he did it remains a mystery. When they will start is not known yet. How he became a great scientist is known to us all. It’s certain. We’ll be late. Is he coming or not? We don’t know What does he want to tell us? We don’t know When will you come back? It doesn’t matter. 四．主语从句需注意的问题 1一个句子作主语时，主句的谓语动词应为单数。 Eg Whether he will come depends on the weather.
2 what 引导的句子作主语时，谓语动词的数由句子的内容决定（即由表语决定)。 What I want is money. What we need are good books What he said is reasonable.
What we will do hasn’t been decided.
3 Where he was born and where he lives now are not clear.
Where and when he was born remains a secret.
两个或两个以上的主从联合做主语，主句谓语动词应为复数。 两个或两个以上的连词引导一个从句，主句谓语动词应为单数。
4 Whether he will come isn’t clear. (不能换成if)
It isn't clear whether /if he will come. (可以与if进行替换) （if不能置于句首）
5. It 作形式主语和it引导强调句的比较
①主语从句常用it作形式主语，一般常用句型为：It is+{名词/形容词/过去分词}+主语从句例如：
It is still a question whether she will come or not. It is strange that you should like him.
It is still unknown which team will win the match. 另外，还有一些比较多见的结构： It turned out that……;
It has been proved that……; It happened/occurred that……; It is well-known that……等等
②而强调句则不同，它的结构是：It+be+被强调部分+that+从句 强调主语：It is the times that produce their heroes.时势造英雄 强调宾语：It is English that Prof.Lin teaches us. 强调状语：It was in shanghai that I saw the film.
判断是否是强调句有一个方法，就是将that以后的“句子的其余部分”拿出来单独看，看有没有缺成分，缺的是什么成分，再把谓语动词后面that前面的那部分，带到你认为缺成分的地方，如果放进去是一句完整的句子了，那就说明是强调句。
6. 用于It is important / natural / necessary / impossible that...句型中, 主语从句应使用虚拟语气, 谓语动词用\\“should + 动词原形\\”的形式, should有时有感情色彩。 It be suggested/ advised/ ordered/requested that sb (should) do sth…
主语从句练习题
一．翻译
1．(谁将去接他)_______________________________________________ is not decided. 2．(哪个班极会赢得这场足球赛)__________________________________ is not clear .
3．(他能否买到飞机票)______________________________________ doesn’t matter much. 4．(我们如何去那里)__________________________________________ is a question. 5．(你刚才告诉我的)_______________________________________ was really a surprise. 6．(他什么时候出国)_______________________________________ is being discussed 7．(他为什么哭)___________________________________________ is not clear.
8．It is clear______________________________________________(他是一个乞丐). 9．(你要请谁)______________________________________________ is not important. 10．(我们将在哪里举行篮球赛)____________________________________ is not clear. 二．找出下列句子中的主语从句及其引导词，并指出引导词是否充当成分，充当什么成分。 1. That we shall be late is certain.
2. That the driver could not control his car was obvious. 3. It is certain that we shall be late.
4. It was obvious that the driver could not control his car. 5. Is it possible that they will come tomorrow？ 6. It is clear that he was telling the truth. 7. It’s probable that we’ll be a little late.
8. What caused the accident is a complete mystery. 9. It worried her a bit that her hair was turning grey.
10. It shocked me that Peter didn’t tell anybody where he was. 11. Who was responsible for the accident is not yet clear. 12. It’s a pity that you can’t go with us. 13. What he did is not yet known.
14. It is said that he has been there many times.
15. It is not yet clear who was responsible for the accident. 16. When they will have the sports meet is still a question. 17. It seems that he has lost something.
18. What he said at the meeting encouraged everyone. 19. What caused the accident was a broken bottle. 20. It remains a problem whether it is true.
21. Whoever breaks the law is sure to be punished. 22. What she looks like doesn’t matter.
23. How this happened is not clear to anyone. 24. Whoever comes is welcome.
25. Whether he’ll come here isn’t clear.
三．用适当的引导词填空。
1. It is likely _____ he is the winner of this game. 很可能他是这场游戏的胜利者。
2. ______ she bought so many dictionaries is not clear.
= It is not clear _____ she bought so many dictionaries. 不清楚她为什么买这么多字典。
3. ________ he was admitted into Beijing University made his teachers and parents happy. 他考上了北大，这让他的老师和父母很高兴。
4. It’s a pity________ you can’t attend my birthday party.
很可惜你不能参加我的生日聚会。
5. _________ we will build a new high school hasn’t been decided. 我们是否要建新高中还没决定呢。
6. __________ breaks the law should be punished. 不管谁违法都应该受到惩罚。
7. It is necessary ______ the problem (should) be solved at once. 很有必要立刻解决这个问题。
8. ________ he was born is unknown. 他生于何时还不知道。
9 It is possible _______ he has stolen the car. 很可能他偷了小车。
10. _______ has broken the glass is unknown. 谁打破了玻璃现在还不知道。 11. _______ he wants is all here. 他所要的东西都在这里。
12. _______ he worked it out is still a secret. 他是如何把它做出来的还是一个秘密
13. _______ they makes in this factory are TV sets. 他们在工厂里所做的东西就是电视机。
14. ________ they would support us was a problem. 他们是否会支持我们还是一个问题。 15. ________ you want is yours. 你要哪个哪个就是你的。
16. ________ we need is money. 我们需要的是钱。
17.________ we arrive doesn’t matter.
什么时候到没有关系。
18. ________ it was done was a mystery. 这是怎样做的是一个谜。
19 ________ this happended is not clear to anyone. 这件事怎样发生的，谁也不清楚。
20. ________ I spend my summer is no business of yours. 我在哪里过暑假不关你的事。
三．选择题。
1. _____ as much as one-fifth of all timber harvested is not used. A. The estimate B. The estimated
C. They are estimated D. It is estimated that
2. _____ some mammals came to live in the sea is not known. A. Which B. Since C. Although D. How
3. _____ we have achieved is attributed to the guidance of our parents. A. Whoever B. Whatever C. However D. That
4. _____ wealthy does not necessarily mean that a man is greedy. A. For the reason that he is B. Just because he is C. The reason of being D. That he is
5. Although ___ happened in this developed country sounds like science fiction, it could occur elsewhere in the world.
A. which B. what C. how D. it
6. _____ she had forgotten to take her notebook. A. That occurred to her B. She occurred that C. To her that occurred D. It occurred to her that 7. I am sure that _____ she said is wrong. A. which B. all C. this D. what
8. We lost our way in the forest, and ____ made matters worse was that it was getting dark. A. that B. which C. it D. what 9. _____ or not is still uncertain.
A. He’s coming B. If he is coming C. That coming D. Whether he’s coming 10. It’s _____ he’ll be able to come.
A. doubt whether B. doubtful C. doubt it D. doubtful whether
11. ______ he is at work in the heart of the big city or at home in the quiet suburb, Dick’s life is tied to machines.
A. Whether B. Till C. If D. Unless 12. _____ he saw both surprised and frightened him. A. That B. When C. What D. Which 13. _____ is warm sunshine.
A. What do we all need. B. What all we need C. What we need D. What we all need
改错：
1. Where shall we spend the holiday isn’t decided. 2. Your have made a mistake is a fact. 3. That is certain that we can win.
4. No matter who leaves the room last ought to turn off the lights. 5. It is important that a student learns a foreign language.
答案：一、翻译
1. Who will pick him up
2. Which class will win the football match 3. Whether he can buy the plane ticket 4.How we will go there
5. What you told me just now 6. When he will go abroad 7. Why he cries
8. that he is a beggar 9. Who you will invite
10.Where we will hold the basketball match
二、略
三、1.that 2. Why ;why 3. That 4. that 5. Whether 6. Whoever 7. that 8. When 9. that 10. Who
11. What 12. How 13. What 14. Whether 15. Whichever 16. What 17. When 18. How 19. How 20. Where
改错
1 we shall
2 that you have 3 It is
4 whoever 5 should learn
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