分娩时，能协助胎先露在骨盆内完成内旋转和仰伸动作的是( )
A．子宫收缩力
B．腹肌收缩力
C．膈肌收缩力
D．肛提肌收缩力
参考答案：D
下面各句中均有一处错误，请找出并改正。
1. This's my family.
2. Who's that men?
3. I loves my father and mother.
4. Who are that girl?
5. Who's your name?
氯化钠水溶液的共晶温度为（）℃。
A.-5.2
B.-10.2
C.-15.2
D.-21.2
