Part two: language Knowledge
Section A (15 points)
Directions: Beneath each of the following sentences there are 4 choices marked A, B, C and D. Choose the one answer that best completes the sentence.
21. --- Time passes quickly, doesn’t it?
--- Yes. It will be only two months_______we take the 2010 College Entrance Examination.
A．since B．after  C．before      D．When