新概念英语第一册语法总结：过去进行时过去进行时表示过去正在进行的动作，经常用在when, while, as引导的状语从句中。结构：was/were+doingWhen my husband was going into the dining room this morning, he dropped some coins on the floor.Their father was watching TV while they were having dinner.变疑问句将be动词移到句首Was their father watching TV while they were having dinner.变否定句在be动词后面加 notTheir father was not watching TV while they were having dinner.
