bài này thì theo mình là như thế này:(nếu sai thì bảo mình nha)

C)

1. I looked at the bookcase and saw an interesting story book ....ON......... the top shelf.

2 ....ON........... sunny days we usually go on a picnic

3. I usually listen ...TO........ pop music, because I'm interested ....IN........ it.

4. Mary was born ....ON..... 20th March .....IN....... 1982.

5. We had to work everyday ......IN........ last summer.

6.. .....AT........ Christmas I'd like to visit my relatives.(khi mà Christmas chỉ đứng một mình thì dùng at ở trước,còn khi dùng on thì Christmas phải kèm theo chữ day.)

VD :at Christmas

       on  Christmas Day.   

7. I last saw him ..in.......... last March.

8. Section 5 is .....on......... the first floor of the Prep School.

9. You mustn't smoke ..........in..... a bus.

10. Ahmet's grandmother died ....in....... 1990 .......at...... the age of 81.

11. Were there many people ......at ....... the concert ?

12. He speaks quite good French. He studied .....in...... Paris for a year.

Nếu bạn ko hiểu thì có thể đọc qua ảnh dưới đây nha