过去进行时的疑问句例句包括：
1. What were you doing at 8 o'clock last night？
2. Why was she crying when I saw her？
3. Where were they going when you met them？
4. Were you cleaning the house at this time yesterday？
5. Was Toby doing his homework then？
6. Were they cleaning the house at this time yesterday？
7. I was walking in the street when someone called me.
8. Was John doing his homework at 8:00 yesterday evening？
9. He was studying for his exam yesterday evening.
10. She was cooking dinner when we arrived.
11. They were playing chess at 8 o'clock last night.
12. He was singing when I arrived.
这些例句展示了过去进行时在不同情境下的应用，包括询问过去某个时刻正在进行的动作、原因、地点等。