主语从句超全讲解加练习

Grammar

Grammar

主语从句： 主语从句：做主语用的名词性从句，因其在复合句中做主语， 做主语用的名词性从句，因其在复合句中做主语， 又称主语从句，引导主语从句的有连词that , 又称主语从句， whether, 连接代词who ,what ,which, 连 接副词when,where, how, why等。

1)从属连词：that, whether等. )从属连词： , 等 that 引导主语从句只起引导作用，本身无实 引导主语从句只起引导作用， 际意义，在主语从句中不充当任何成分， 际意义，在主语从句中不充当任何成分，但 不能省略。 不能省略。 That he will win is certain.他肯定会赢。 他肯定会赢。 他肯定会赢 Whether he’ll come here isn’t clear. 他 是否会来这里还不清楚。 是否会来这里还不清楚。

注意: 注意 由that 引导的主语从句有时为了使句子结构平衡, 头重脚轻” 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。 例如: 主语 而把从句放在后面。 例如 1. That he will refuse this piece of advice is impossible. It is impossible that he will refuse this piece _______________________________________ of advice. _______________________________________

*it为形式主语 为形式主语2.That they should like each other is natural. It is natural that they should like each other. _____________________________________

这样就构成了下面一些常用句型: 这样就构成了下面一些常用句型 1) It is + n. +从句 从句 It is a pity/shame that... 遗憾的是 遗憾的是…… It is a surprise that…令人惊奇的是 令人惊奇的是… 令人惊奇的是 It is a fact that… …是事实 是事实 It is common knowledge that… …是常识 是常识 It is a pity that 很遗憾)we lost the match. *_______________(很遗憾 很遗憾 It is a fact that 这是事实)he cheated in the *______________(这是事实 这是事实 exam.

2) It is + adj. +从句 从句 It’s certain that… 肯定 肯定… It is possible that... 很可能 很可能…… It is unlikely that... 不可能 不可能…… It is obvious that… 很明显 很明显… It is necessary \important \natural\... that… +(should) +do… It is possible that 很可能)she will come *_________________(很可能 很可能 back tomorrow. It is obvious that 很明显)this measure is *_________________(很明显 很明显 effective.

3) It +不及物动词 从句 不及物动词+从句 不及物动词 It happened that... 碰巧…… 碰巧 It occurred to me that…我突然想起 我突然想起… 我突然想起It happened that 刚好)I *________________(刚好 came into the office 刚好 at that time. *____________________(我突然想起 forget to 我突然想起 It occurred to me that 我突然想起)I sent the letter.

4) It + be +过去分词+从句It is said that... 据说…… 据说 It is known to all that... 众

所周知 众所周知…… It is reported that... 据报道 据报道…… It is believed that...据信 据信……;人们相信 人们相信…… 据信 人们相信 It is suggested that + (should)do... 建议 建议…… ) It must be admitted that…必须承认 必须承认…… 必须承认 It cannot be denied that… 不可否认…… 不可否认 It must be pointed out that…需指出的是 需指出的是…… 需指出的是

It is reported that 据报道)20 people were *___________________(据报道 据报道 killed in the accident. It is suggested that 建议 *______________________(建议 建议)we should eat more vegetable and do more exercise.

2.连接代词 连接代词who ,what ,which, whatever, 连接代词 whichever, whoever (Who, whom, which, what可 可以和ever构成合成词，和what一样引导从句，ever起到 构成合成词， 一样引导从句， 以和 构成合成词 一样引导从句 起到 强调作用。此类主语从句不能用形式主语it引导 引导， 强调作用。此类主语从句不能用形式主语 引导，它们在 句子中担任成分，不能省略，语序为陈述语序) 句子中担任成分，不能省略，语序为陈述语序

What many scientists believe is that the earth is round … Who will take part in the meeting has not been decided. Whoever breaks the law will be punished. Which student will win is uncertain. Whatever was said here must be kept secret. 这里说的话都应当保密。 这里说的话都应当保密。 Whoever makes mistakes must correct them. 凡犯了错误的人都必须改正。

3)连接副词 连接副词when,where, how, why等。 连接副词 ， , , 等Why they suddenly disappeared still remains a mystery. When they will leave is not decided. Where she is from is unknown. How we will paint the house has not been decided.

注意:1)主语从句在句首时，必须由连接词引 )主语从句在句首时， 不能省略这些连接词；但是如果用it 导，不能省略这些连接词；但是如果用 做形式主语，而把主语从句放在句末时， 做形式主语，而把主语从句放在句末时， 从属连词that可以省略。 可以省略。 从属连词 可以省略误：They should like each other is natural. 正：That they should like each other is natural. 正：It is natural (that) they should like each other.

2)如果主语从句放在句首，不能用if引 如果主语从句放在句首，不能用 引 如果主语从句放在句首 但是如果用it 做形式主语， 导，但是如果用 做形式主语，而把主 语从句放在句末时，也可以用if引导 引导. 语从句放在句末时，也可以用 引导 或把if 或把 改为whether误：If Mary really heard him is really doubtful. 正：It was doubtful if Mary really heard him. 正: Whether Mary really heard him is really doubtful.

Complete the sentences using what, whether, where, when, who, why, how or that.W

hat 1.(_____ is needed for success) is your hard work. When/How 2.(______ they will arrive )has been told to the teacher. Where/whether 3.(_____ we will go tomorrow )hasn’t been decided yet. 4.(______ can join in the sport meet) is decided by the teacher. Who 5.(________ it will rain or not) is not clear. Whether

Conclusion: 主语从句作主语时，谓语动词一般用单数形式。 主语从句作主语时，谓语动词一般用单数形式。

主语从句的规律： 找出下列句子中的错误，并总结规律 例1.When will he come is not known. 正：When he will come is not known. 规律一、主语从句一律用陈述语序， 即主语在前，谓语在后。

主语从句的规律：

例2. He will not come to the meeting this evening is true. 正：That he will not come to the meeting this evening is true.规律二、连词that 在从句中无实际意义， 但不能省略。

主语从句的规律： 例3. If the meeting will be put off

has not been decided yet. 正： Whether the meeting will be put off has not been decided yet.规律三、whether 可以引导主语从句， 放在句首，但if不能

主语从句的规律： 例4. That whether he will help others

is a fact.正：That he will help others is a fact. 规律四、主语从句中的连词不能重叠使用。

主语从句的规律：例5. When he will come are a puzzle. 正：When he will come is a puzzle. 规律五、含主语从句的主句谓语动词多用 单数第三人称形式。

主语从句的规律：

1. What he needs is that book. 2. What he needs are some books.规律六、what 引导的主语从句，可根据 表语决定主句动词的单复数形式。

规律七、主语从句为了避免头重脚轻现 象，用 it 做形式主语，而 把从 句放在后面。

That the earth turns around the sun is known to all. It is known to all that the earth turns around the sun.

找出错误，并给出理由： 1.Where shall we spend the holiday isn’t decided. we shall 2.You have made a mistake is a fact. That you have 3. If the policeman will come is not certain. Whether 4. That is certain that we can win. It

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