过去进行时

过去进行时描述以前的动作或事件，而且到说话的时候仍在持续。换句话说，这个时态表达过去未完成或不完整的动作。

它用于：

描述以过去时来写的故事背景，例如："The sun was shining and the birds were singing as the elephant came out of the jungle. The other animals were relaxing in the shade of the trees, but the elephant moved very quickly. She was looking for her baby, and she didn't notice the hunter who was watching her through his binoculars. When the shot rang out, she was running towards the river..."
描述未完成的动作，这个动作被另一个动作或事件给打断了。例如："I was having a beautiful dream when the alarm clock rang."
表达改变心意。例如："I was going to spend the day at the beach but I've decided to get my homework done instead."
与「wonder」连用，让要求的语气变得很客气。例如："I was wondering if you could baby-sit for me tonight."

注：有些动词一般不会用在进行时，只用于一般过去时。

任何动词的过去进行时都是以两个要素构成：Be 动词的过去时 (was/were)，以及主要动词原型 +ing。