3. Complete the table.
1. at: the beginning of last year, 12 o'clock.
=> at + giờ.
2. in: April 2008, the twenty-first century.
=> in + tháng/năm/thế kỉ.
3. on: 25 May 1975, 2 January 1952.
=> on + ngày tháng năm cụ thể.
4. Complete the sentences.
1. was watching - heard
2. found - were digging
3. was standing - saw
4. were working - went
5. was telling - rang
6. was driving - stopped
7. were having - heard
8. was watching - fell
=> S + was/were + V-ing when S + V(past simple): một hành động đang diễn ra thì một hành động khác xen vào.
5. Complete the text.
1. B. were
2. A. decided => Decide (v): quyết định.
3. C. were swimming => S + was/were + V-ing when S + V(past simple).
4. B. were
5. C. saw
6. B. was
7. A. shouted => Shout (v): hét.
8. C. wasn't
