Part 1:

1. wasn't (last week)

2. will / see (tomorrow)

3. didn't finish (yesterday)

4. leaved (ago -> quá khứ)

5. have / sung (ever -> hiện tại hoàn thành)

6. walked (yesterday)

7. 

8. fly (hiện tại đơn)

9. did / sleep (last night)

10. wore (last friday)

11. won't have (next Christmas)

12. is / work (at the moment -> hiện tại đơn)

13. have / been (before -> hiện tại hoàn thành)

14. won't buy (next month)

15. spoke (last summer)

Part 2:

1. dangerous

2. do

3. more

4. are 

5. the concerts

6. easier

7. much

8. written

9. shortest

10. than

Part 3:

1. than

2. the

3. many

4. much

5. any 

6. do

7. most

8. last

9. there

10. to

11. next

12. how 

13. last (Did ở đầu câu -> Quá khứ)

14. ever (have you ever been ...?)

15. a (a little)