选修7重点语法汇总Unit19一.名词性从句在复合句中起名词性作用的句子叫名词性从句。

名词性从句可分为主语从句、表语从句、宾语从句和同位语从句。

主语从句引导主语从句的连接词主要有三类：连接词that，whether，if；连接代词what，who，whose，whatever，whichever，whoever等；连接副词when，where，why，how等。

1.连接词that，whether，if引导①That the college will take in more new students this year is true.今年这所大学将招收更多新生是真的。

②It was doubtful whether/if the manager knew the details of the plan.经理是否知道计划的细节还不确定。

【注】(1)if引导的主语从句主语从句不可放在句首，只能放于it作形式主语的句子中。

Whether引导的语从句既可放在句首也可放在句尾，if和whether在句中都不充当成他，意为“是否”(2)形式主语it替代主语从句。

常见的it替代主语从句的句式主要有以下几种：A. It+系动词+形容词(possible,easy,necessary,polite)+that从句。

如：It is quite clear that the whole project is doomed to failure. 很清楚，整个计划注定要失败。

B. It+系动词+名词(no wander,a pity,an honor)+that从句。

如：It is no wander he was so sad.难怪他这么伤心呢。

C. It+be+v．ed(known,said,expected,thought,reported,etc.)形式+that从句。

如：It is announced that the plan has been successfully carried out. 据宣布计划已经顺利实施。

D．It seems/happens+that从句It happened that he passed by the house.碰巧他经过那栋房子。

2．连接代词引导①What we can’t get seems better than what we already have. 我们得不到的东西似乎比我们拥有的东西好。

②who the letter was from is still unknown. 这封信是谁寄出的还不清楚。

③Whichever of you gets here first will get the prize. 你们当中第一个到达这里的人将获得奖项。

3．连接副词引导①How acupuncture reduces and relieves pain is unclear. 针灸是如何减轻和解除疼痛的还不清楚。

②why dinosaurs suddenly disappeared still remains a mystery. 恐龙为什么突然消失了还是个谜。

宾语从句引导宾语从句的连接词主要有三类：连接词that，whether，if等，连接代词what，who，whose，whatever，whichever，whoever等，连接副词when，where，why，how等。

1．连接词that，whether，if引导①I think(that)you should turn to the teacher for help. 我认为你应该向老师寻求帮助。

②I don’t know if/whether he still lives here after so many years. 我不知道这么多年后他是否还住在这儿。

【注】whether/if都意为是否。

一般情况下，它们可以互换，口语中常用if，但以下情况中，只能用whether。

(1)与or not紧接连用时。

如：Let me know whether or not you can come. 请让我知道你是否能来。

(2)作介词的宾语从句时。

如：We are interested in whether you will attend the meeting. 我们对你是否参加会议感兴趣。

2．连接代词what，who，whose，whatever，whichever，whoever等如：①She asked me whose handwriting was the best in the class. 她问我班上谁的书法最好。

②I’ll just say whatever comes into my mind. 我想到什么就说什么。

3.连接副词引导when，where，why，how等①Do you know when the ancient Olympic Games began? 你知道古代的奥运会是什么时间开始的吗?②I’ve been thinking about how we can make the newspaper more interesting. 我一直在考虑如何使我们的报纸更用趣。

4．宾语从句的语序在宾语从句中要用陈述句语序。

如：①He asked me when we could set out the next day. 他问我第二天什么时候可以出发。

5．宾语从句的时态(1)主现从随意当主句的谓语动词是一般现在时时，其宾语从句的时态可以是任何适当的时态。

①She says(that)she works from Monday to Friday. 她说她周一至周五上班。

(从句是一般现在时)②she says(that)she will leave a message on his desk. 她说她要在他桌子上留个便条。

(从句是一般将来时)③She says(that)she has never been to Mount Emei. 她说她从来没有去过峨眉山。

(从句是现在完成时)(2)主过从过当主句的谓语动词是一般过去式时，其宾语从句的时态一般要用适当的过去时态。

如：①He said there were no classes yesterday afternoon. 他说昨天下午没有课。

(从句是一般过去时)②He said that he was going to take care of the baby. 他说他会去照看这个婴儿。

(从句是过去将来时) ③He said that they were having a meeting at that time. 他说他们那时正在开会。

(从句是过去进行时)(3)真理永存在当宾语从句是表达客观真理和规律的句子时，其时态仍旧用一般现在时。

如：①The teacher told us that nothing is difficult if we put our hearts into it．老师告诉我们世上无难事，只怕有心人。

【注】在使用宾语从句时需要注意下面几点：(1)动词find，feel，think，consider，make，believe，guess，suppose，assume等后有宾语补足语时，则需要用it作形式宾语，而将that宾语从句后置。

如：①I think it necessary that we take plenty of boiled water every day．我认为每天多喝开水是有必要的。

②I have made it a rule that I keep diaries．我每天写日记成了惯例。

(2)hate，like，take，owe，have，take for granted等表示―喜欢；痛恨；认为的动词或动词短语和see to表示―注意，留意‖后有宾语补足语时，需要用it作形式宾语而将宾语从句后臵。

如：①I hate it when they talk with their mouth full of food．我讨厌他们满嘴食物说话。

表语从句常由连接词that，whether；连接代词who，whom，whose，which，what，whoever，whomever，whichever，whatever；连接副词when，where，how，why引导。

【注】1.that引导表语从句时只起连接作用，在从句中不充当任何成分，但是不能省略。

2.wh-类连词引导的表语从句在从句中充当成分并有实际意义，主要作主语，宾语，表语和状语等。

1．连接词引导①The reason for his absence is that he hasn’t been informed. 他缺席的原因就是他没接到通知。

②The question remains whether they will be able to help us. 问题还是他们能否帮我们。

2．连接代词和连接副词引导①The problem is who will take charge of this shop. 问题是谁将接管这家店铺。

②That is when I realized the importance of journalism. 那时我才意识到新闻工作的重要性。

【注】(1)as/as if/as though引导的表语从句常跟在特定动词后面，如seem，appear，look，taste，sound，feel等。

如：①It sounds as if someone is knocking at the door. 听上去好像有人在敲门。

②At that time,it seemed as though I couldn't think of the right word. 当时我似乎怎么也想不出一个恰当的字眼来。

(2)当主句的主语是reason时，表语从句一般由that引导，这种用法常见于句型The reason why…is that…。

如：The reason why he came late was that he got up late．他来得晚是因为起床晚了。

同位语从句同位语从句在句子中作某一名词的同位语，一般位于该名词之后，说明该名词的具体内容。

这些名词常见的有idea，fact，news，hope，belief，thought，doubt，promise，suggestion，order等。

1．通常用连词that引导同位语从句，that无词义，也不作句子成分，但不能省略。