1. This is the first time (that) I have written to my lover. (thì hiện tại hoàn thành, dấu hiệu là the first time)

2. Her father has worked as an engineer since 1990. (Dấu hiệu là since)

3. He has been able to drive since he was 18.

4. Have you visited Buckingham Palace yet? (dấu hiệu là yet)

5. It is the most enjoyable concert (that) they have ever been. (dấu hiệu là ever)

6. I have never tasted such a delicious cake. (dấu hiệu là never)

7. It is the first time (that) I have ridden on a camel. 

8. Since his wife died in 1978, Charles has lived alone. 

9. Have they sent the text messages to their friends yet?

10. This is the best party (that) I have ever been to.