月经周期中雌、孕激素对下丘脑的反馈为
A.雌激素的正反馈
B.孕激素的正反馈
C.雌激素的负反馈
D.孕激素的负反馈
E.雄激素的负反馈
参考答案:A, C, D
Had the boy worked harder, he ______ the exam.
A.must have got through
B.could get through
C.ought to get through
D.would have got through
社会工作的基本对象包括()。
A.孤儿
B.妇女
C.残疾人
D.精神病患者
E.因失业而生存困难者