Dưới đây là những từ có thể điền vào chỗ trống trong đoạn văn:

17. **wakes** (đánh thức)
18. **broken** (bùng phát)
19. **crowded** (đông đúc)
20. **rest** (nghỉ ngơi)

Vậy đoạn văn hoàn chỉnh sẽ như sau:

“In the fire station, an alarm is (17) **wakes** up the firemen. A fire has just (18) **broken** out somewhere in the big city.

The streets are (19) **crowded** with traffic. Taxis are bringing tired people from the airport and the railroad stations to the hotels. They hope to (20) **rest** a few hours before their busy day in the big city.”