Chào cháu :))
3.
1. was going
2. swam
3. drank
4. was seeing
5. was
6. beat
7. asked
8. told
9. was staying
10. had
4.
1. Yesterday, when he carried a suitcase, he was dropping it on his foot.
2. He was breaking his leg when he ski last month.
3. He was sitting down on the chair when I painted it.
4. Lan sat in the garden when a wasp was stinging her on a nose.
5. As we drove down the hill, a strange object was appearing on the sky.