题型:单项选择题 紧急避孕是指在无保护性交后72小时内服用甾体激素药物或120小时内放置宫内节育器以防止非意愿妊娠。请问计算紧急避孕效果较科学的方法为()。A.百分率计算法B.妇女年计算法C.预期妊娠数减去实际妊娠数除以预期妊娠数乘100%D.寿命表法E.百分之百减去失败率 查看答案
题型:选择题 Tom _______ the TV set for $500,which was much cheaper than he had expected.A.bought B.paid C.cost D.spent 查看答案