16. After David had gone home, we arived.

Cấu trúc

-After + past perfect, simple past

17. Before we took a look around the shops, we had had lunch.

Cấu trúc

- Before +simple past, past perfect

18. When we got out of the office, the light had gone out.

Cấu trúc

-When + simple past, past perfect

19. By the time we started out work, she had explained everything clearly 

Cấu trúc

-By the time + past simple, past perfect

20. The building where he lives is very old.

-Đại từ quan hệ where thay thế cho danh từ chỉ nơi chốn

21. I will tell you something which you didn't know before. 

- Đại từ quan hệ which thay thế cho danh từ chỉ vật.

22. I'll never forget the day when i met you. 

-Đại từ quan hệ when thay thế cho danh từ chỉ thời gian 

23. Although it was cold, Tom still went swimming 

-Although + clause