______to school is good for our health. [ ]
A. Walk
B. To walk
C. Walking
D. Walks
C
写出你熟悉的一个定理:______,写出这个定理的逆定理:______.
胎体纵轴与母体纵轴的关系称为
A.胎方位B.胎势C.横产式D.胎产式E.胎先露