1. It – b) was raining.
2. The dog – e) wasn't eating its food.
3. I – a) working at lunchtime.
4. We weren't – d) cleaning her teeth.
5. They – c) weren't waiting for me.
6. She was – f) was studying last night.
Ответ: 1 – b, 2 – e, 3 – a, 4 – d, 5 – c, 6 – f