How nervous we are ______ the coming high school entrance exams _____ June 15th.
| A．thinking of ; on | B．to think of; on |
| C．thinking of ; in | D．to think of; in |
Good books help us ___________ a whole new world to me .
| A．turn up | B．look up | C．get up | D．open up |
There is no air _______ water on the moon .
| A．and | B．but | C．or | D．with |
They don’t know what ___________ the problem .
| A．to do | B．do | C．to do with | D．do with |
Don’t try to do everything at once. Take it a bit _______________.
| A．at times | B．at a time |
| C．at all times | D．at that time |
We __________ obey the traffic rules.
| A．must | B．have to | C．may | D．can |