【语法专项讲解】

    名词性wh-从句
  
    1）由wh-词引导的名词从句叫做名词性wh-从句。wh-词包括who, whom,. whose, whoever, what, whatever, which, whichever等连接代词和where, when, how, why等连接副词。wh-从句的语法功能除了和that-从句一样外，还可充当介词宾语、宾语补语和间接宾语等，例如：

    主语： How the book will sell depends on its author.　书销售如何取决于作者本人。

    直接宾语：In one's own home one can do what one likes.　在自己家里可以随心所欲。

    间接宾语：The club will give whoever wins a prize.俱乐部将给得胜者设奖。

    表语： My question is who will take over president of the Foundation.　我的问题是谁将接任该基金会主席职位。

    宾语补足语：She will name him whatever she wants to. 她高兴给他起什么名字就取什么名字。

    同位语：I have no idea when he will return. 我不知道他什么时候回来。

    形容词宾语：I'm not sure why she refused their invitation.　 我尚不能肯定她为什么拒绝他们的邀请。

    介词宾语：That depends on where we shall go.那取决于我们去哪儿。

    2）wh-从句作主语也常用先行词it做形式主语，而将wh-从句置于句末，例如：

    It is not yet decided who will do that job. 还没决定谁做这项工作。

    It remains unknown when they are going to get married. 他们何时结婚依然不明。

    It 作形式主语

    It 作形式主语代替主语从句，主要是为了平衡句子结构，主语从句的连接词没有变化。

    用it 作形式主语的结构

     (1) It is ＋名词＋从句

    It is a fact that …                       　事实是……

    It is an honor that                      　　……非常荣幸

    It is common knowledge that            　　  ……是常识

     (2) it is ＋形容词＋从句

    It is natural that…                         很自然……

    It is strange that…                         奇怪的是……

     (3) it is ＋不及物动词＋从句

    It seems that…                              似乎……

    It happened that…                           碰巧……

     (4) it ＋过去分词＋从句

    It is reported that…                        据报道……

    It has been proved that…                    已证实……

    3. 主语从句不可位于句首的五种情况

    (1) it 引导的主语从句不可居于复合句句首。

    (2) It is said, (reported) …结构中的主语从句不可提前。例如：

    It is said that President Jingo will visit our school next week. (right)

    That President Jiang will visit our school next week is said. (wrong)

    (3) It happens…, It occurs… 结构中的主语从句不可提前。例如：

    It occurred to him that he failed in the examination. (right)

    That he failed in the examination occurred to him. (wrong)

    (4) It doesn't matter how/whether …结构中的主语从句不可提前。例如：

    It doesn't matter whether he is wrong or not. (right)

    Whether he is wrong or not doesn't matter. (wrong)

    (5) 含主语从句的复合句是疑问句时，主语从句不可提前。例如：

    Is it likely that it will rain in the evening? (right)

    Is that will rain in the evening likely? (wrong)

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