助动词用法

be动词，情态动词，助动词do/does的用法区别及练习 助动词，顾名思义就是帮助动词完成疑问及否定的，本身没有什么含义。主要的助动词有be,do,will,have等，其用法详述如下： 一、⑴ 由连系动词am，is，are构成的句子：变一般疑问句时把am，is，are提到句子的前面，句尾用问号即可。变否定句时直接在am，is，are后面加not即可。例如： 肯定句:He is a student. 一般疑问句: Is he a student? 否定句: He is not a student. 画线提问: 对he提问: Who is a student? 对 a student 提问: What is he? (2)was 是am,is的过去式，were是are的过去式，若句子中有以上两词时，变疑问句及否定句方法与（1）相同。 二、(1) 由情态动词can, may,will ，shall等构成的句子: 变一般疑问句时把 can, may,will ，shall提到句子的前面,句尾用问号即可.变否定句时直接在can,may,后面加not即可. 例如: 肯定句: She can swim. 一般疑问句: Can she swim? 否定句: She can not swim. 画线提问: 对she提问: Who can swim? 对swim提问: What can she do? （2）could,might,would,should是can,may,will,shall的过去式，若句子中有以上两词时，变疑问句及否定句方法与（1）相同。 三、（1）由行为动词构成的句子: 需要加助词do或does. 变一般疑问句时把do/does放在句子前面. 变否定句时把don’t/doesn’t放在动词的前面。要注意观察动词的形式并对号入座。一般疑问句和否定句的动词三单式都要变回原型。 play-----do plays-----does 例如: 肯定句: They play football after school. He plays football after school. 一般疑问句: Do they play football after school? Does he play football after school? 否定句: They don't (do not) play football after school. He doesn’t’ play football after school. 画线提问: 对they/he提问: Who plays football after school? 对play football提问: What do they do after school? What does he do after school? 对after school提问: When do they play football? When does he play football? （2）did是do和did的过去式，变一般疑问句时把did放在句子前面. 变否定句时把didn’t放在动词的前面, 要注意观察动词的形式并对号入座。一般疑问句和否定句的动词都要变回原型。