成本核算基本关键点是（）A、归集B、费用C、部门D、分配

2，4，8，16的倒数之和是多少？

任意自然数（0除外）的倒数都小于它本身。[ ]

The thief ________ in from the kitchen window as the door was closed.

A．may climb

B．must have climbed

C．could have climbed

D．should have climbed

声音在( )中传播速度最快。

A．钢
B．海水
C．空气
D．地幔岩石

由中央军委领导国防教育工作。