`1.` While I looked for my keys, I remembered that I left them at home.

Remember + to V: Nhớ sẽ làm gì ở hiện tại hoặc tương lai.

Look for sth: Tìm kiếm thứ gì.

While QKTD, QKĐ
`2.` Anna used to play badminton when she was at school.

S + used to + V-inf : Ai đó từng làm gì
`3.` When I got into bed, I fell asleep immediately.

fell asleep : (v) ngủ thiếp đi 

`4.` When I finally found the house, I knocked on the door.

QKD : S + Ved/V2
`5.` After Jill gave Nick his books, she went home.

After + S + V (past perfect), S + V (past simple)
`6.` Maria used to live in Sweden when she was a child.

S + used to + V-inf : Ai đó từng làm gì
`7.` I used to get up early when I went sailing.

S + used to + V-inf : Ai đó từng làm gì
`8.` The Vikings sailed to North America a thousand years ago.

sail ... to : đi từ đâu đến đâu

QKD : S + Ved/V2
`9.` Sue was sure she had seen the tall man before.

QKHT :  S + had + P2