牛津英语上海版9年级上册Module3知识点及语法点

M3 动词不定式和动名词的句法功能比较 一、作主语 ⒈不定式作主语 动词不定式作主语时，句子的谓语动词常用单数，其位置有以下两种： (1)把不定式置于句首。如： To get there by bike will take us half an hour. (2)用it作形式主语，把真正的主语不定式置于句后，常用于下列句式中。如： ①It＋be＋名词＋to do It's our duty to take good care of the old. ②It takes sb+some time+to do How long did it take you to finish the work? ③It＋be＋形容词＋for sb＋to do It is difficult for us to finish writing the compositionin a quarter of an hour. ④It＋be＋形容词＋of sb＋to do It is stupid of you to write down everything the teachersays. ⑤It seems(appears)＋形容词＋to do It seemed impossible to save money. 在句型③中，常用表示客观情况的形容词，如：difficult,easy,hard,important,impossible,necessary 等；在句型④中，常用careless,clever,good,foolish,honest,kind,lazy,nice,right,silly,stupid,wise等 表示赞扬或批评的词。在不定式前的sb，可看作其逻辑主语。这一句式有时相当于Sb is＋形容词＋to do句式 ，如：It'skind of you to help me with my English.=You are kind to helpme with my English. ⒉动名词作主语 Learning without practice is no good. 动名词