过去进行时四大句型
肯定句：
主语+was/were+doing+其他
Wewerehavingclassatthistimeyesterday.
昨天这个时候我们正在上课。
否定句：主语+wasn't/weren't+doing其他Weweren'thavingclassatthistimeyesterday.
我们昨天这个时候没上课。
一般疑问句：
—Was/Were+主语+doing+其他？
—Yes,主语+was/were./—No,主语+wasn't/weren't.
-WasJohndoinghishomeworkat8:ooyesterdayevening?
-Yes,hewas./No,hewasn't.
特殊疑问句：特殊疑问词+was/were+主语+doing+其他?
WhatwereyoudoingwhenIcalledyoulastnight?
昨天晚上我给你打电话的时候，你正在干什么？