He’s aiming ________a prize. That is why he puts his heart ________ his work.
| A．at; of | B．to; off |
| C．for; away | D．at; into |
If you are travelingthe customs are really foreign to your own, please do as the Romans do.
| A．in which | B．what | C．when | D．where |
Isn't it time you got down tothe papers?
| A．mark | B．be marked | C．being marked | D．marking |
I just wonder ____ that makes him so excited.
| A．why it does | B．what he does | C．how it is | D．what it is |
Some people fear that ________ air pollution may bring about changes in _______ weather around the world.
| A．/; the | B．the; / | C．an; the | D．the; a |
The doctor must be _______ 24 hours a day, 7 days a week in the boarding school.
| A．on call | B．by hand | C．in sight | D．on spot |