1. 肯定句形式：主语+动词过去式+其他

I was an English teacher one year ago.

一年前我是一名英语老师。

I bought a yellow dress yesterday afternoon.

昨天下午我买了一条黄裙子。

2. 否定句形式：①was/were+not; ②在行为动词前加didn't，同时还原行为动词

I wasn't an English teacher one year ago.

一年前我不是一名英语老师。

I didn't buy a yellow dress yesterday afternoon.

昨天下午我没买一条黄裙子。

3. 一般疑问句：①was/were提到句首; ②Did+主语+动词原形+其他?

Were you an English teacher one year ago?

一年前你是一名英语老师吗?

Did you buy a yellow dress yesterday afternoon?

昨天下午你买了一条黄裙子吗?

4. 特殊疑问句：特殊疑问词+一般疑问句

What were you one year ago?

一年前你是做什么的?

When did you buy a yellow dress?

你什么时候买了一条黄裙子?