第1个回答 2013-02-04
助动词一般在肯定句中不出现,一般do,does用于一般现在时,did用于一般过去式。
它的出现是帮助①有行为动词的肯定句②变成否定句或者疑问句,它是构成有行为动词的否定句和疑问句的助手,所以叫助动词,无实际意义,不是行为动词(行为动词有实际意义)。
例:(1) I am a student. 否: I am not a student. 疑: Are you a student?
解析:因为原句没有行为动词,只有be动词,所以变否定句或疑问句不需要向助动词求助
(2) She can swim. 否: She can't swim. 疑: Can she swim?
解析:因为原句没有行为动词,只有情态动词,所以变否定句或疑问句不需要向助动词求助
(3) He plays football every day. 否: He doesn't play football every day. 疑: Does he play football
everyday?
解析:因为原句有行为动词play,所以变否定句或疑问句要向助动词求助,出现助动词后,行为动词变成原型。
原创整理,希望能够帮到你!不懂请追问O(∩_∩)O