Scientists are convinced ___ the positive effect of laughter ____ physical and mental health.
| A．of; on | B．by; in |
| C．of; at | D．on; at |
We have moved into a four-room flat so far. Our room is between _____.
| A．Mary’s and Helen’s | B．Mary and Helen’s |
| C．Mary and Helen | D．Mary’s and Helen |
I am in ______ charge of the class which was in ______ charge of my wife.
| A．不填；the | B．不填；不填 | C．the; 不填 | D．the; the |
._______a group of students, the foreigner entered the museum.
| A．Following | B．To follow |
| C．Followed | D．Being followed |
.----I can’t find Jack. Where did you see him this morning?
----It was in his factory _______he worked.
| A．where | B．which |
| C．that | D．on which |
Not until the taxi disappeared in the distance ________her handbag was gone.
| A．Mary had found | B．had Mary found |
| C．did Mary find | D．Mary found |