皮带机打滑的原因是（）。
A.皮带机运输物料过载
B.驱动滚筒未包胶或胶皮损坏
C.驱动滚筒处有水或潮料
D.胶带松长
参考答案：A, B, C, D
元宵节客家人要吃哪种应节食品？
A decorator bought a bolt of defective cloth that he judged to be usable, in which ease the cost would be $0.80 per usable yard. If it was later found that only of the bolt could be used, what was the actual cost per usable yard ？（）
A.$0.60
B.$0.90
C.$1.00
D.$1.20
E.$1.70
usable, in which ease the cost would be $0.80 per usable yard. If it was later found that only 
of the bolt could be used, what was the actual cost per usable yard ？（）