名词性从句与非谓语
一、名词性从句与动名词
名词从句是属于名词性的，而英语中的三大非谓语只有动名词和不定式具有名词的特征，可以当成名词来使用。因此，名词类的从句可以被化简成动名词和不定式。
由陈述句变来的名词性从句，即由that引导的名词从句一般简化成动名词来表达，通常采用动名词复合结构的形式；由疑问句变来的，即由whether或what等引导的名词从句一般简化为不定式。
1. that引导的主语从句与动名词
  直接用动名词的复合结构来替换主语从句，放在句首作主语。
例: 1 (1) It surprised us that John won the marathon.
      It 作形式主语，真正的主语是that引导的从句。
      (约翰赢得了马拉松比赛，这真让我们吃惊)
(2)That John won the marathon surprised us.
That 引导的从句作主语，谓语是 surprised 。
(3)John`s winning the marathon surprised us.
将(2)中的主语从句John won the marathon变为动名词的复全结构John`s winning the marathon来充当句子的主语。即主语从句就变成了动名词形式。
例: 2 (1)That he lost the game came as a surprised to everybody.
That 引导的主语从句that he lost the game 作主语，谓语是came。
(他在比赛中失利，这让每个人都很意外）
(2)His losing the game came as a surprise to everybody.
      将that he lost the game变为动名词的复合结构his losing the game来充当句子的主语。
2. that引导的同位语从句与动名词
  简化that引导的同位语从句时，也是变同位语从句为一个动名词的复合结构。但是，因为英语中没有“名词+动名词”这样的结构，所以要在同位语从句修饰的名词后面加上一个介词，来连接名词与动名词，同时表达同位语关系。能担当此任的介词通常是of ，偶尔可以用about等。于是句子由原来的同位语从句结构“名词+that同位语从句”变成了一个动名词结构“名词+of+动名词的复合结构”。
例: 1
(1)There was no chance that Davy would come from the battle alive. that引导的同位语从句Davy would come from the battle alive补充说明先行词chance,以表明chance 的具体内容。
(大卫不可能从战场上生还)
(2)There was no chance of Davy coming from the battle alive.
  将(1)中的同位语从句that Davy would come from the battle alive变为动名词的复合结构Davy coming from the battle alive,放在介词of 后面，来补充说明chance。这里的of 表示同位说明关系。
例:2
(1)We were greatly encouraged by the news that china had launched another man-made satellite.
  that引导的同位语从句补充说明先行词news,以表明news的具体内容。
(2)We were greatly encouraged by the news of china having launched another man-made satellite.
  把(1)中的同位语从句变为动名词的复合结构China having launched another man-made satellite.放在介词of后面，来补充说明news。这里的of表示同位说明关系。
3. that引导的宾语从句与动名词
由that引导的宾语从句的简化较为复杂，因为它可以转换成动名词，也可以转换成不定式，这主要与主句谓语动词的用法密切相关。
例：1
(1) I consider that I will emigrate to America in the future.
  that引导的宾语从句充当动词consider的宾语。
(2) I consider emigrating to America in the future.
例句(1)中的宾语从句I will emigrate to America in the future变为动名词emigrating to America in the future.这是因为consider的后面要接动名词，不能接不定式，因此该从句要简化为动名词。
例：2
(1) Jane`s mother insisted that she should go swimming with her brother.
That引导的宾语从句充当动词insisted的宾语。
(简的妈妈坚持要求她和她哥哥一起去游泳)
(2) Jane`s mother insisted on her going swimming with her brother.
例句(1)中的宾语从句she should go swimming with her brother变为动名词的复合结构her going swimming with her brother,并且之前还添加了介词on，这是因为insist的后面要接介词on之后才能接宾语。
例：
(1) I hope that I can drive to work in my own car.(我希望能开着自己的车去上班）
    that引导的宾语从句充当动词hope的宾语。
(2) I hope to drive to work in my own car.
  例句(1)中的宾语从句I can drive to work in my own car变为不定式to drive to work in my own car,这是因为hope 的后面要接不定式，不能接动名词，因此该从句要简化为不定式。
由以上例子可知：宾语从句是简化成动名词还是不定式形式，完全取决于主句的谓语动词。
二、名词性从句与不定式
event是什么词性由疑问句变来的名词性从句，即由whether或what等引导的名词从句一般简化为不定式，主要是宾语从句简化为不定式。此时的宾语从句中往往含有情态动词，比较多见的是should或can\could。
例：1
(1) She can`t decide whether she should go with him or stay home.
(2) She can`t decide whether to go with him or (to) stay home.
由whether引导的宾语从句whether she should go with him or stay home变为不定式whether to go with him or stay home,这里的不定式具有“应该”的情态意义。
她还没有决定，应该和他一起去还是就呆在家里。
例：2
(1) I haven`t decided whether I should vote for Clint.
(2) I haven`t decided whether to vote for Clint.
我还没有决定是否应该给克林特投标。
例：3
(1) I don`t know what I should do.
(2) I don`t know what to do .
由what引导的宾语从句what I should do变为不定式what to do,这里的不定式具有“应该”的情态意义。
例：4
(1) Please tell me how I can get to the bus station.
(2) Please tell me how to get to the bus station.
由how引导的宾语从句变为不定式how to get to the bus station,这里的不定式具有“能够”的情态意义。