1. Đáp án:
1. He went to the swimming pool because he liked swimming.
2. They knew dinner was at nine o'clock.
3. Helen ate too many sweets.
4. I bought the newspaper in the shop.
5. We got up at eight o'clock and went to school.
6. Did she buy the newspaper in the shop over there?
7. Did they do their homework in the evening?
8. Did they have a good holiday?
9. Did they find any animals in the forest?
10. Was it dark when she got up in the morning?
11. They always enjoyed going to the zoo.
2. Giải thích:
- Câu 1, 3, 4, 5, 6, 7, 8, 10 vẫn giữ nguyên vì đã đúng ở thì quá khứ đơn.
- Câu 2 cần thêm "was" để hoàn chỉnh câu "They knew dinner was at nine o'clock."
- Câu 9 cần đổi "animal" thành "animals" vì "any" thường đi với danh từ số nhiều.
- Câu 11 cần đổi "enjoy" thành "enjoyed" để phù hợp với thì quá khứ.