Dear children，this is ______ unusual exam．______ exam is very important to you．Please take it easy．Wish you good results．（ ）
| A． |
an； The |
B． |
a； the |
C． |
an；A n |
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
Which of the two subjects do you like，P．E．or music？
_______．They are really interesting．（ ）
A．NeitherB．BothC．None