Let's put the piano over there， __________ the wall．（ ）
A．aboveB．againstC．acrossD．around
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