英语过去进行时的用法之：并行操作，即：过去连续并行动作
当你在同一个句子中使用过去进行时和两个动作时，它表达了两个动作同时发生的意思。这些动作是平行的。
例如：
I was studying while he was cooking dinner.
我在学习，而他在做晚饭。
While Alan was reading, Tim was watching TV.
当艾伦在读书时，蒂姆在看电视。
Were you listening while he was talking?
他说话的时候你在听吗?
I didn't notice when I wrote, so I made several mistakes.
我写信时没注意，所以犯了几个错误。
What were you doing while you were waiting?
你在等的时候在做什么?
Thomas doesn't have a job, and neither do I.
托马斯没工作，我也没工作。
They are having dinner, discussing their plans and having a good time.
他们在吃晚饭，讨论他们的计划，玩得很开心。
在过去进行时中，当两个动作同时在发生，while后面解连续动词，而when后面既可以接连续动词有可以接不连续动词。