19. Lan used to go to school by bicycle.

20. We used to use oil lamp.

21. He didn't use to get up late in the morning.

22. I used to work as a tour guide for that travel agency.

Giải thích:

- Used to + V: Đã từng

- Any more: Ko lần nào nữa

- Be used to doing sth: Quen với làm gì -> Chưa từng

- No longer: Không còn 

$\text{19.}$ Lan used to go to school by bicycle.

$\text{20.}$ We used to use oil lamp.

$\text{21.}$ He didn't use to get up late in the morning.

$\text{22.}$ I used to work as a tour guide for that travel agency.

→ S + used to + V-inf + O 

→ S + didn't + use to + V-inf + O 

→ Did + S + use to + V-inf + O ? 

$#Keisha$