煤矿现行的窄轨轨道，根据铺设的轨距分为（）三种。
A.900mm
B.762mm
C.600mm
D.1350mm
参考答案：A, B, C
The young nurse was very nervous when she in her first operation. [ ]
A. resisted
B. insisted
C. assisted
D. assigned
流量计壳体上的部件和阻尼筒，应能承受（）倍最大工作压力。
A.1倍
B.1.5倍
C.2倍
D.2.5倍
