这四种从句合称名词性从句。它们在主句中充当主语、表语.docVIP

主语从句、表语从句、宾语从句、同位语从句在复合句中起名词的作用，这四种从句合称名词性从句。它们在主句中充当主语、表语、宾语或同位语，都不能用逗号与主句分开。 ■主语从句 1、定义：先找到句子的谓语，主句的谓语前面的从句，叫做主语从句。 Why he left wasnt important.(wasnt是主句的谓语动词，why he left做主语从句) That she became an artist may have been due to her fathers influence.(may have been due是主句的谓语动词，that she became an artist做主语从句) 2．主语从句能用it作形式上的主语。常以it作形式主语的句型有(注意：从句不一定是由that引导，也可由其他词引导)：A. It+be+形容词(obvious, true, natural, surprising, good, wonderful, funny, possible, likely, certain, probable, etc.)+that从句。如：It is certain that she will do well in her exam. 毫无疑问她考试成绩会很好。It is probable that he told her everything. 很可能他把一切都告诉她了。B. It+be+名词词组(no wonder, an honour, a good thing, a pity, no surprise, etc.)+that从句。如：It’s a pity that we can’t go. 很遗憾我们不能去。It’s no surprise that our team should have won the game. 我们没赢这场比赛真意外。C. It+be+过去分词(said, reported, thought, expected, decided, announced, arranged, etc.)+that从句。如：It is said that Mr. Green has arrived in Beijing. 据说格林先生已经到了北京。It is reported that China has sent another man-made earth satellite into orbit.据报道中国又成功地发射了一颗人造地球卫星。D. It+seem, happen等不及物动词及短语+that从句。如：It seems that Alice is not coming to the party at all. Alice似乎不来参加晚会。It happened that I was out that day. 碰巧我那天外出了。E. It+doesn’t matter (makes no difference, etc.)+连接代词或连接副词引起的主语从句。如：It doesn’t matter whether she will come or not. 她是否来这无关紧要。It makes no difference where we shall have the meeting. 我们在哪里开会毫无区别。F. 当that引导的主语从句出现在疑问句中时，要以it作形式主语，而把主语从句后置。如：Is it true that the scientist will give us a lecture next week? 下周那位科学家将给我们作报告是真的吗？Does it matter much that they will not come tomorrow? 他们明天不来很要紧吗？G. 当主语从句出现在感叹句中时，要以it作形式主语，而把主语从句后置。如：How strange it is that the children are so quiet! 孩子们这么安静真奇怪！ H.更多例句： It is strange that he knows nothing about it. It is a pity that he cant swim. It happened that he wasnt in that day. It is said that there has been an earthquake in India. Its a puzzle how life began. It doesnt matter much where we live. Is it known where he went？ It is