妇女结婚后,不一定都在短期内受孕,即使在()内发生性关系。
参考答案:排卵期
(x-y)10的展开式中,x7y3的系数与x3y7的系数之和等于 ______.
I()half of the English novel,and I,ll try to finish it at the weekend.
A.read
B.have read
C.am reading
D.will read