只有非均质体、透明的彩色宝石才可能观察到多色性。
参考答案：对
— ___________ anybody hurt?
— No, everyone was safe.[ ]
A. Does
B. Did
C. Were
D. Are
液压防爆绞车运转中司机应随时观察各压力表指示压力，控制压力应为（）Mpa。
A、7.5～9
B、6.5～8
C、5.5～6
