自有阶级以来,警察普遍存在于各个历史时期的各种类型的国家。( )
参考答案:对
Though brought up in Los Angeles, Steven Davidson spent his whole life in New York.
A.mostly
B.constantly
C.roughly
D.merely
分娩时的主要产力是 ()
A.腹肌收缩力
B.腹肌和膈肌收缩力
C.肛提肌收缩力
D.子宫收缩力
E.骨骼肌收缩力