动名词和现在分词都是在动词词尾加ing, 二者都可以带宾语、被副词修饰,但是二者的语法作用有差异。
动名词所起作用是名词,而现在分词所起的作用是形容词和副词,如
【例句1】I like eating ice cream. (我喜欢吃冰淇淋。[动名词短语eating ice cream是名词性短语,作like的宾语])
【例句2】The subject interesting him at the moment is Greek history. (他目前感兴趣的课程是希腊史。[现在分词短语interesting him是形容词词性短语,对主语subject修饰])
【例句3】Reviewing her bank statement, Ann started to cry. (安查看她的银行对账单,开始哭泣。[现在分词短语Reviewing her bank statement, 作时间状语])
英语的名词也可以起形容词作用,所以动名词也可以在名词前面,如
【例句4】She has a sleeping bag. (她有一个睡袋。)
起形容词作用的现在分词其实是限制性从句的改写,比如【例句2】中The subject interesting him是对The subject that interests him的缩写。
但是动名词不能变为限制性从句,比如【例句4】不能改写成为(按常规语境理解,袋子是不能睡觉的)
【例句5*】She has a bag which is sleeping.
动名词当作形容词使用时,前面的动名词往往是被修饰名词的目的,如【例句4】可改写成
【例句6】She has a bag for sleeping.
然而,语言总是刻意弄出歧义的例子来,如(Noam Chomsky著名例子)
【例句7】Flying planes can be dangerous.
【例句7】的Flying planes既可以解读为动名词,即The practice of flying a plane,也可以解读现在分词,即Planes that fly或Planes when they are flying。