贯穿于整个分娩过程的主要力量是()
A．子宫肌收缩力
B．腹肌收缩力
C．肛提肌收缩力
D．骨骼肌收缩力
E．膈肌收缩力
参考答案：A
They _____ England and they will be back next week. [ ]
A. have gone to
B. have been to
C. have gone in
D. has been on
某一滑动面为折线型的均质滑坡，其主轴断面及作用力参数如表所示，问该滑坡的稳定性系数FS最接近下列（）数值。
A.0.80
B.0.85
C.0.90
D.0.95
