英语中动名词的作用

动词不定式和动名词做主语，动词原形不能作主语。Ⅰ.动名词和不定式做主语的相同点 1.不定式短语和动名词做主语时，常常为了保持句子的平衡，用it来做形式主语，如： It is not easy to learn English well. It is no use asking him for help. 2.如果主语用了不定式,表语和宾语也要用不定式;主语用了动名词,表语和宾语也要用动名词,这在英语中称为对称性,如: To see is to believe. = Seeing is believing. (眼见为实) (85)It is better to stay home than _A__ out. A. to go B. going C. go D. gone Ⅱ.动名词和不定式做主语的不同点 1.不定式做主语常表示具体的某一动作;表示泛指或一般的抽象的概念时,多用动名词,如: (92)_B_ is a good form of exercise for both young and old. A. The walk B. Walking C. To walk D. Walk 2.在”There/It +be+ no use(good/help/need)”之后常用动名词做主语,而少用不定式,如: It /There is no use crying over the split milk. It /There is no help taking this medicine. ★但是如果该句型中用了for引出不定式的逻辑主语,就只能用不定式,如: (93) There is no good for us to do that exercise. 3.不定式可以和when, where, how, what, whether等连用,在句子中做主语,宾语和表语,而动名词则不能,如: How to solve the problem is a hot potato. Where to put the box seems hard to decide. Whether to do it hasn’t been decided. What to do next is up to you.