拨道时,指挥者距拨道人员一般不少于()m。
A、30
B、50
C、80
D、100
参考答案:B
I am fond of music while my sister likes reading novels. It seems that we have nothing ______.
A.in trouble
B.in common
C.in place
D.in need
精子获能的主要部位是()
A.睾丸
B.附睾
C.输精管
D. * *
E.子宫和输卵管