(1)表示时间  at+时间点：在…时刻，在…点钟，在…岁时

            on+某天或某天的某个时间：在某日、星期几、某日早中晚等

            in+时间段：在…期间，在…以后，在…时间内

            by+时间：在…之前，不迟于…，常与完成时连用

(2)表示方位：in/on/to/off

(3)表示部位

1. 常用介词的意义区别

16. How long do you think it is____ she arrived here?

A. when              B. that                  C. before             D. since

1-5 BCDAB   6-10 BDBCA   11-16 CCCBCD

15. To his joy, the day he looked forward to____ at last?

A. coming           B. come               C. came               D. have come

14. Mr Reed made up his mind to devote all he had to____ some schools for poor children.

A. set up              B. setting up        C. have set up      D. having set up

13. What do you consider____ to her?

A. to happen        B. happening       C. happened        D. happens

12. Who did the teacher, as well as the monitor, ____ an article for the wall newspaper?

A. has write         B. has written      C. have write       D. have written

11. The air quality in Beijing as well as in the neighboring cities we once spent much time____ better and better.

A. in getting        B. having got       C. in is getting     D. has got

10. We will do everything we can____ our city.

A. to save            B. save                C. saving             D. saved

9. Mr Wang was much disappointed to see the washing machine he had had____ went wrong again.

A. it repaired       B. to be repaired  C. repaired         D. repairing