在英语学习中，掌握动词的时态是非常重要的基础。其中，一般过去时和过去进行时是两个经常被混淆的概念。为了帮助大家更好地理解和运用这两种时态，我们特别准备了以下专项练习题。

一、选择题

1. I ________ my homework when you called me yesterday.

A. was doing B. did C. have done D. do

正确答案：A

解析：当描述过去某个时间点正在进行的动作时，应该使用过去进行时。句子中的“when you called me”表明动作发生在过去某个具体的时间点，因此应选择A选项。

2. She ________ at the bus stop for half an hour before the bus arrived.

A. waited B. was waiting C. has been waiting D. had waited

正确答案：B

解析：根据句子结构，“before the bus arrived”表示在过去某个时间之前发生的动作，而“waited”则表示完成的动作。这里强调的是等待这个动作持续了一段时间，所以应该选择B选项。

二、改写句子

3. Tom was reading a book when his friend came.

改为一般过去时：

Tom read a book and his friend came.

4. We were having dinner when the power went out.

改为一般过去时：

We had dinner and the power went out.

三、填空题

5. Last night, while I ________ (watch) TV, someone knocked on the door.

答案：was watching

6. When he ________ (get) home, it was already dark outside.

答案：got

通过以上练习，我们可以看到，一般过去时用于描述过去发生的动作或事件，而过去进行时则用来描述过去某一时刻正在发生的动作。希望这些题目能帮助你更清晰地区分并熟练运用这两种时态。继续加油吧！