Be动词用法
be动词（am、is、are）+not、
情态动词can+ not、
助动词（do、does） + not
如何将一个肯定的陈述句改为否定句：
1、看句中有无be动词，如有，直接在be动词后+ not。
2、看句中有无情态动词，如有，直接在情态动词后+ not。
3、如上述二者都没有，就应用助动词+ not。分四个步骤：
（1）肯定陈述句中本来是没有助动词的，要加上去，位置在主语（某人或某物）后，动词前。
（2）确定助动词用do、does，根据句中动词，动词是原形的助动词就用do，动词是第三人称单数的助动词就用does，
（3）在助动词后加not。
（4）原句中动词假如发生变化就要恢复成原形。
强调一点，有some的要考虑是否要用any。
一般疑问句
一般疑问句
如何将一个肯定的陈述句改为一般疑问句：
1、看句中有无be动词，如有，把be动词提到句首即可。
2、看句中有无情态动词，如有，把情态动词提到句首即可。
3、如上述二者都没有，就应把助动提到句首。分四个步骤：
（1）肯定陈述句中本来是没有助动词的，要加上去，位置在主语（某人或某物）后，动词前。
（2）确定助动词用do还是does，根据句中动词，动词是原形的助动词就用do，动词是第三人称单数的助动词就用does
（3）把助动词后提到句首。
（4）原句中动词假如发生变化就要恢复成原形。
强调一点，有some的要考虑是否要用any。
过去式
表示过去发生的动作或事件， 常和表示过去的时间状语连用，如yesterday, last night, the day before yesterday, 3 days ago,
含有be动词的句子， 将动词变为过去式，am, is的过去式为was，are的过去式为were
I was at the butcher’s.
You were a student a year ago.
The teacher was very beautiful ten years ago.
★变疑问句将be动词移动到句首
Were you at the butcher’s?
Were you a student a year ago?
Was the teacher very beautiful ten years ago?
★变否定句在be动词后面加not
I was not at the butcher’s.
You were not a student a year ago.
The teacher was not very beautiful ten years ago.
★肯定回答否定回答
Yes, I was. No, I was not.
Yes, you were. No, you were not.
Yes, he/she was. No, he/she was not.
★特殊疑问句：
What did you do?
(必背)
不含有be动词的句子，将动词变为过去式
I finished my homework yesterday.
The boy went to a restaurant.
The Sawyers lived at King Street a year ago.
★变疑问句在句首加did， 动词变为原型
Did you finish your homework yesterday?
Did the boy go to a restaurant?
Did the Sawyers live at King Street a year ago?
★变否定句在主语和动词之间加did not
I did not finish my homework yesterday.
The boy did not go to a restaurant.
The Sawyers did not live at King Street a year ago.
★肯定回答及否定回答
Yes, I did. No, I didn’t.
Yes, he did. No, he didn’t.
Yes, they did. No, they did not.
