过去进行时是英语语法中描述过去正在进行的动作或事件的时态，由"was/were" + "动词的现在分词"构成。它可以用于描述过去某一时刻的动作，或表达过去的持续性动作或状态。在否定和疑问句中，"was/were"作为助动词使用。理解和掌握过去进行时对提高英语水平非常重要。
构成
过去进行时的构成是由"was/were" + "动词的现在分词"，例如：
- I was walking to the store.
- They were studying for their exams.
用法
过去进行时一般用于以下情况：
1. 描述过去某一时刻正在进行的动作
例如：
- At 8 o'clock yesterday evening, I was watching TV.
- When I saw him, he was playing basketball.
2. 表达过去的持续性动作或状态
例如：
- He was living in New York for three years before moving to Los Angeles.
- The children were sleeping when the storm hit.
注意事项
-
过去进行时一般用于描述过去某一时刻正在进行的动作，所以它和过去简单时态的区别在于强调动作正在进行中。
-
在过去进行时当中，"was/were"是助动词，所以在进行否定和疑问句时需要借助助动词来构成，例如：
- Was he studying when you called him?
- They weren't watching the movie when I arrived.
