The little boy his seat to an old lady on the crowded bus．（ ）
A．lentB．offeredC．tookD．brought
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
Is this your son's sweater？
No，______ is on the chair behind the desk．（ ）
A．hersB．yoursC．his