Cấu trúc "Used to": đã từng..
+/ S + used to + V(nguyên mẫu)
-/ S + didn't use to + V(nguyên mẫu
?/ Did + S + use to + V(nguyên mẫu)?
(+ là thể khẳng định; - là thể phủ định; ? là thể nghi vấn)
Đặt câu
I used to play badminton with my best friend
She used to live in an apartment
He didn't use to have a dog
We didn't use to wear glasses
Did your uncle use to smoke?