主语从句以及练习题.doc

主语从句：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 ，whether， 连接代词who ，what ，which， 连接副词when，where， how， why等。1）连词：that， whether等.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 he will win is certain.他肯定会赢。Whether hell come here isnt clear. 他是否会来这里还不清。注意: 由that 引导的主语从句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。 例如: 1. That he will refuse this piece of advice is impossibleIt is impossible that he will refuse this piece of advice.it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: 1) It is + n. +从句 It is a pity/shame that. 遗憾的是 It is a surprise that令人惊奇的是 It is a fact that 是事实 It is common knowledge that 是常识2) It is + adj. +从句 Its certain that 肯定 It is possible that. 很可能 It is unlikely that. 不可能 It is obvious that 很明显 It is necessary important natural. that3) It +不及物动词+从句 It happened that. 碰巧 It occurred to me that我突然想起4) 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 + (should）do. 建议It must be admitted that必须承认 It cannot be denied that 不可否认 It must be pointed out that需指出的是 2.连接代词who ，what ，which, whatever, whichever, whoever (Who, whom, which, what可以和ever构成合成词，和what一样引导从句，ever起到强调作用。此类主语从句不能用形式主语it引导，它们在句子中担任成分，不能省略，语序为陈述语序)Whoever breaks the law will be punished3)连接副词when，where， how， why等。 When they will leave is not decided.Where she is from is unknown注意:1）主语从句在句首时，必须由连接词引导，不能省略这些连接词；但是如果用it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。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引导，但是如果用it 做形式主语，而把主语从句放在句末时，也可以用if引导.或把if 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。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。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。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。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.Exercises :1. D has helped to save the drowning girl is worth praising.A.Who B.The one C.Anyone D.Whoever2.It was A he said disappointed me.A.what ;that B.that; that C.what;what D.that;what3. B well go camping tomorrow depends on the weatherA.If B.Whether C.That D.Where4. A he said at the meeting surprised everybody present.A.What B. That C.The fact D.The matter5. B was to return to school.A.That really interested him B.What really interested himC.Which really interested him D.That interest him really6、_A_ he made an important speech at the meeting was true.A. That B. Why C. What D. How 7、_B_well go camping tomorrow depends on the weather .A If B Whether C That D Where 8._D_ is known to us all that America is a developed country .A Which B as C W