桥式起重机上主要采用（）钢丝绳。
A.交绕
B.顺绕
C.石棉芯
参考答案：A
—What a beautiful factory! I want to work in it.
—Well, workers _______ very much here. [ ]
A. need
B. are needing
C. are needed
D. will need
下列成本费用中，不属于半变动成本的是( )。
A．修理费 B．电话费C．材料费 D．燃料费
