航空器由10000ft下降到4000ft,下降率600ft/min,下降时间为()分钟。
A.10
B.16
C.18
D.15
参考答案:A
As the robbery was taking place, I stood by calmly, not________, but calling 110 immediately. [ ]
A. shouted
B. shouting
C. to shout
D. having shouted
金合金全冠抛光所用的抛光剂是()。