Now, she's ___________ her face. [ ]
A. washes
B. washed
C. washing
答案：C
Mary has two brothers, ________ are doctors.
A．both of they
B．both of whom
C．both of them
D．whom of both
WHO规定正常生育者精子活动力在射精后60min内，a+b级精子应（）
A.>30%
B.>40%
C.>50%
D.>60%
E.>70%
