David is a fantastic singer ______ can play different kinds of music．（ ）
| A． |
which |
B． |
who |
C． |
whom |
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
Is this your son's sweater？
No，______ is on the chair behind the desk．（ ）
A．hersB．yoursC．his
I bought ______ useful dictionary yesterday．_______dictionary is very cheap．（ ）
A．a； AB．a； TheC．an； The