助動詞種類較多，以下主要介紹be,do,will,have等助動詞的使用： 一、be動詞作助動詞 ⑴ 由連繫動詞am，is，are構成的句子：變一般疑問句時把am，is，are提到句子的前面，句尾用問號即可。變否定句時直接在am，is，are後面加not即可。例如： 肯定句:He is a student. 一般疑問句: Is he a student?否定句: He is not a student. 畫線提問: 對he提問: Who is a student? 對 a student 提問: What is he? (2)was 是am,is的過去式，were是are的過去式，若句子中有以上兩詞時，變疑問句及否定句方法與（1）相同。 二、情態動詞作助動詞 (1) 由情態動詞can, may,will ，shall等構成的句子: 變一般疑問句時把 can, may,will ，shall提到句子的前面,句尾用問號即可.變否定句時直接在can,may,後面加not即可. 例如: 肯定句: She can swim. 一般疑問句: Can she swim? 否定句: She can not swim. 畫線提問: 對she提問: Who can swim? 對swim提問: What can she do? （2）could,might,would,should是can,may,will,shall的過去式，若句子中有以上兩詞時，變疑問句及否定句方法與（1）相同。 三、do作為助動詞 （1）由行為動詞構成的句子: 需要加助詞do或does. 變一般疑問句時把do/does放在句子前面. 變否定句時把don’t/doesn’t放在動詞的前面。要注意觀察動詞的形式並對號入座。一般疑問句和否定句的動詞三單式都要變回原型。 play-----do plays-----does 例如: 肯定句: They play football after school. He plays football after school.一般疑問句: Do they play football after school? Does he play football after school? 否定句: They don't (do not) play fo

助動詞不分肯定與否定

助動詞do用來幫助動詞進行形式變換，無實際意義。

 助動詞有兩種形式 --原形do, 三單式does. 助動詞否定有兩種形式--原形否定 don't, 三單否定doesn't like----do not like (簡稱don't like) likes---- does not like(簡稱doesn't like) 口訣：助動詞，變得勤，謂語動詞用原形。 want---- don't want wants---- doesn't want have----don't have has----doesn't have

如: 1. I have a dictionary. 改謂語 have--don't have I don't have a dictionary. 

2. They like the green lake. 改謂語like--don't like They don't like the green lake.

 3. She has two yellow rulers. 改謂語：has--doesn't have She doesn't have two yellow rulers. 

4. He wants a new car. 改謂語：wants--doesn't want He doesn't want a new car.