Bài 1

1. Emily **had never seen** the Southern Lights before she **moved** to Finland.
2. When I **got** to English club, no one **was** there. They **had gone** somewhere else.
3. My aunt **had been taking** care of the seniors at the local nursing home for six years by the time she **changed** her job.
4. Julie **turned** up at the station ten minutes late and **saw** that her train **had just departed**.
5. Mr. Davis **arrived** at his parents' place and **found** that they **had left** for dinner.
6. I **didn't know** Francesca before I **met** her at a concert two years ago.
7. Because William and Charles **had read** poor reviews of the film, they **didn't join** us for going to the cinema.
8. As Tony **had not spoken** in front of so many people before, he **was** extremely nervous.
9. We **called** to tell Martha about the plane crash, but she **had heard** it on the evening news five minutes earlier.
10. I **didn't play** tennis with Tom yesterday afternoon because I **had already played** with Harry that morning.

1. She'd travelled to all European countries by the time she turned eighteen.
   2. Alex and Hudson had forgotten to bring a map because they got lost in the forest.
   3. They hadn't studied English and French before they moved to Canada last year.
   4. Will and his family had lived in Leeds before they moved to London two years ago.
   5. The baby had fallen asleep before her parents came home from work at eight.
   6. I thought that my younger sister hadn't asked me that difficult question before.
   7. Sue and Miranda hadn't brought a raincoat because they got wet.
   8. Timothy's grandparents had owned the car for ten years before they sold it.
   9. Mr. and Ms. Gomez didn't notice the traffic light had turned red.
   10. Alex and his brother had ordered noodles but the waiter served them rice.

2. **Giải thích**: 
   - Các câu trên được sắp xếp lại để tạo thành những câu có nghĩa và đúng ngữ pháp. Mỗi câu đều sử dụng thì quá khứ hoàn thành (had + V3) để diễn tả một hành động xảy ra trước một thời điểm hoặc một hành động khác trong quá khứ. Việc sắp xếp từ ngữ theo đúng thứ tự giúp câu trở nên rõ ràng và dễ hiểu hơn.