6.
1.has been trying 2. have just finished 3. haven't bought
4. has been cleaning 5. Has Nick been working 6.haven't cooked yet
7. Have you read 8. has been working 9. have been knowing
10. Have you seen
7.
1. shouldn't 2. should 3. should 4. shouldn't 5. should 6. should
7. should 8. shouldn't