轧机调整不良，两边压下量不一致，易产生（）。
A、中间波浪
B、单侧波浪
C、镰刀弯
D、楔形
参考答案：C
It was not _____ she took off dark glasses _____ I realized she was a famous film star.[ ]
A. when; that
B. until; that
C. until; when
D. when; when
前厅为客人提供贵重物品保管服务中，每个保险箱有（）把钥匙。
A.一
B.三
C.二
D.四
