Scientists are convinced _______the positive effect of laughter ______ physical and mental health.
| A．of ; at | B．by ; in | C．of ; on | D．on ; at |
Look out the traffic when crossing the road.
| A．at | B．of | C．for | D．with |
The bridge is 1000 meters length.
| A．with | B．in | C．at | D．on |
The two countries were between 1989 and 1992.
| A．peace | B．at no war | C．at peace | D．at peaceful |
The oil must be used up, the light went out.
| A．for | B．because | C．since | D．as |
---Poor Tom! He will have to work all the next month.
---Luckily, the basketball games are held.
| A．except | B．except that | C．except when | D．except for |