1. It was snowing when I left home this morning.
2. It was a sunny afternoon and people were sitting on the grass in the park. Then suddenly it started to rain.
3. Were you talking to your mum on the phone when the bus arrived?
4. They discovered this unusual plant when they were walking in the wood.
5. We were climbing the hill when we saw a snake.
6. He dropped his camera on the floor while he was dropping his backpack.