Is Mr Brown driving here？
I'm not sure．He ______ come by train．（ ）
| A． |
may |
B． |
shall |
C． |
need |
D． |
must |
The school sports meeting will be_______ because of the heavy rain．（ ）
A．put upB．put onC．put off
If more people give up driving cars，the air will get much _______ in a few days．（ ）
A．cleanB．cleaner
C．the cleanest
The number of people in the city ______ about seven million now．（ ）
A．areB．hasC．is
It's necessary for you _______the classroom clean，class．（ ）
A．keepB．keepingC．to keep
I didn't realize he was a famous scientist ______ you told me．（ ）
A．untilB．becauseC．since