集装箱船设置双层船壳的主要原因是______。
A、提高抗沉性
B、提高船体扭转强度
C、作为减压舱
D、作为货仓

单项选择题在唐德斯(F.C.Donders)的减法反应时实验中，A、B、C三种反应时分别代表简单反应时、选择反应时和辨别反应时，它们的关系为A.RTB＞RTA＞RTCB.RTC＞RTB＞RTAC.RTC＞RTA＞RTBD.RTB＞RTC＞RTA

单项选择题听力原文： A Boeing 727 aircraft with 51 passengers and 10 crew on board has crashed into a mountain side just outside the Columbia capital, BurgdA.Police and rescue workers said everyone was killed when the plane exploded scattering wreckage over a wide areA.The crash happened shortly after take-off when the plane was unable to gain enough height to clear the mountains. The aircraft belonged to Airpodorpia Airline, but it had been chartered by Air France for the route from Burgda to Airpodorpia Capital, Quito.__________ people were killed during the air crash.A.61B.51C.41D.10