具有约束骨骼，主司关节运动作用的是（）
A.十二经脉
B.奇经八脉
C.十二经筋
D.十五别络
E.十二经别
参考答案：C
It was three months later _____ he completed the job with difficulty.
A．since
B．before
C．while
D．that
简述深井泵电机经常检查及长期停用泵的巡查内容。
