_____ Mary _____ two brothers? [ ]
A. Do; have
B. Does; have
C. Do; has
D. Does; has
B
组装一套较为复杂的实验装置,正确的组装顺序一般是( )
A.自右到左,再自下而上
B.自上而下,再从左到右
C.自下而上,再从左到右
D.可随意组装
嵌顿性肩先露通常不易引起()。
A.病理缩复环
B.宫腔内感染
C.脐带脱垂
D.胎盘早剥
E.胎死宫内