1. 概念: 表示过去某一时刻或某段时间内正进行的动作。 2. 构成: was/were + 动词现在分词 We were not sleeping at home. Was he feeling well? 3. 用法: a: 表示某一时刻正进行的行为, 与特定的过去时间状语连用,常见的时间有: at 8 last night, at this time at that time, at that moment 等。 What were you doing at 10 yesterday morning? I was writing a letter to my father at that moment.