21. sử dụng cấu trúc be unable to do something = không thể làm gì

John was unable to find the right house

22. dùng cấu trúc used to do something = đã từng làm gì

Richard used to smoke cigarettes ....

23. If he doesn't phone his wife immediately, he won't get any information (unless = if not)

24. He didn't forget, neither did she.

25. I remember being taken to a well-known theatre in the city (chuyển sang câu bị động, remember ving = nhớ đã làm gì)

26. the doctor suggested Mrs White (should) try go to bed earlier

27. The course lasts (for) three months

28.Travelling by airplane always makes me nervous