Ex.3

1 goes

2 go

3 didn't use to

4 going

5 be

6 study

7 play

8 play

Ex.8

1 My father used to live in small village when she was a girl. (Câu này hơi lạ vì my father là cha thì phải là con trai hay tiếng anh là "he, a boy", nhưng ở đây lại là "she, a girl". Cậu xem lại đề nhé)

2 There did not use to be many vehicles on the road before.

3 We used to cycle to school two years ago.

4 Now there are more traffic accidents.

5 My brother used to go swimming when he was a child.

Giải thích: 

(+) S+used to+V(nguyên thể)

(-) S+didn't use to+V(nguyên thể)

(?) Did+S+use to+V(nguyên thể)?