1, giving - give

2, when - since

3, did you do - were you doing

4, was cooking - cooked

5, saw - have seen

6, has already left - had already left

7, recovering- to recover

8, taking off - to take off

9, going out - to go out

10, buying - buy

11, to use - use

12, to check - checking

Chúc bạn học tốt nha!

1, giving - give

2, when - since

3, did you do - were you doing

4, was cooking - cooked

5, saw - have seen

6, has already left - had already left

7, recovering- to recover

8, taking off - to take off

9, going out - to go out

10, buying - buy

11, to use - use

12, to check - checking

13, to smoke - smoking 

14, didn’t speak - hadn’t spoken

15, will have - would have 

16, had been - were

17, didn’t say - hadn’t said

18, we can - we could

19, am - were

20, knew - had known

21, not missed - hadn’t missed

22, checking- checked 

23, has sent - has been sent

24, came - come

25, had gone - went

26, up - off

27, off - up

28, turn to - turned to

29, show of - show off

30, off - of