精子在女性生殖管道寿命为12~24小时。
参考答案：错
Tom _____ his father and his father _____ young.[ ]
A. looks like; looks like
B. looks like; looks
C. looks ; looks like
D. looks; looks
影响龋病流行的有关因素不包括（）
A.氟的摄入量
B.糖的摄入量
C.钙的摄入量
D.糖的摄入频率
E.饮食习惯
