英语中的各种从句详解.doc

一．名词性从句 在句子中起名词作用的各种从句统称为名词性从句。这类从句在句中可担任主语、表语、宾语和同位语，名词从句可以分为主语从句、表语从句、宾语从句和同位语从句。 1.主语从句 在句子中担当主语的是一个句子，这个从句就叫作主语从句。主语从句可以由下列连词、连接代词和连接副词引导，且不能省略。 连词：that, whether 连接代词：what, whatever, who, whoever 等 连接副词：when, where, how, why (1)由连词that, whether引导的主语从句 连词that, whether在从句中的作用只是引导主语从句，它在从句中不担任成分，不能省略，且由that, whether引导的主语从句，多用it多形式主语 e.g That the earth is round is true.=It is true that the earth is round.地球是圆的，是一个事实。 Whether he’ll come or not hasn’t been decided.= It hasn’t been decided whether he’ll come or not. (2)由连接代词或连接副词引导的主语从句 连接代词who, which和连接副词when, where, how, why都可以引导主语从句，它们分别在从句中担任主语、宾语和状语，不能省略，翻译时，不能把它们译为疑问句，由它们引导的主语从句，也可以用形式主语it引导 e.g Who let out the news remained unknown. =It remained unknown who let out the news. When we’ll start is not clear. =It is not clear when we’ll start.我们何时出发还不清楚。 (3)以关系代词what, whatever, whoever, whomever, whichever引导的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。 e.g What he said at the meeting is important.他在会上所说的事情是重要的。 Whoever leaves the office should tell me.无论是谁离开办公室都应该告诉我。 (4)用it作形式主语的主语从句结构 a. It is +名词+从句 It is a fact that… 事实是……类似的名词还有：a pity； no wonder；等。b. It is +形容词+从句It is necessary that … 有必要……It is clear that … 很清楚……It is likely that … 很可能……It is important that … 重要的是……It is essential that he should be here by the weekend .周末之前，他应该到这里是必要的。c. It is +过去分词+从句It is said that … 据说…… It is reported that … 据报道……d. It +不及物动词+从句It seems that … 好像是…… It happened that… 碰巧……It now appears that they are in urgent need of help. 2. 宾语从句 用作宾语的从句叫宾语从句。 1.引导宾语从句的关联词有三类： (1) 从属连词that。如： He told us that he felt ill. 他对我们说他感到不舒服。 I know he has returned. 我知道他已经回来了。 注： that在引导宾语从句时也并不是任何情况下都可以省略。在以下情况下，that不能省略。 1. Everybody could see what happened and that Tom was frightened. and连接两个宾语从句，that宾语从句放在and的后面时，that不能省略。 2. I know nothing about him except that he is from the south. that引导的宾语从句作介词宾语时，that不能省略。 主句谓语动词与that从句之间有插入语，that不可省略。 (2)从属连词if/whether。如： I doubt whether he will succeed. 我怀疑他是否会成功。 I don’