选词填空。

1. Have you done your homework _____? (for, just, yet)

2. I have _____ been to Chengdu. (ever, never, yet)

3. He has _____ washed the dishes. (already, ever, for)

4. He has worked there _____ he left school. (already, just, since)

5. Have you cleaned your room _____? (for, just, yet)

6. She has known Sam _____ nine years. (for, never, since)

7. They have _____ arrived. (ever, just, yet)

8. Have you _____ ridden a horse? (ever, for, yet)

9. She has known Fred _____ they were at primary school. (already, just, since)

10. We haven't completed the project _____. (already, for, yet)