知识点：1 过去进行时a) 过去进行时由“was/were+动词ing形式”构成。以动词work为列，其肯定式，否定式，疑问式以及简略答语见下表：肯定式：I/He/She/It was working. We/You/ They were working.否定式：I/He/She/It was not working. We/You/They were not working.疑问式和简略答语：Was I working? Yes, you were. Was he working? No, he wasnt.【注意】was not常简略为wasnt; were not常简略为werentb) 过去进行时的用法：过去进行时表示过去某一时刻或某一段时间正在进行的动作。这一特定的过去时间，除有上，下文暗示以外，一般用时间状语来表示2 not until直到才。表示动作在某时之前尚未开始，直到此时动作才开始。notuntil可以用after或when来代替，但主句谓语动词要用肯定形式。Until为连词时后
