推轮椅上下楼梯错误的是（）。

A.多采用二人式或四人式

B.二人式，轮椅背向楼梯，前轮抬起，后轮触地

C.二人式，一人抬前轮，另一人向后托，逐级而上

D.二人式，下楼梯相反，轮椅背向楼梯

E.四人式，轮椅前后方各二人，抬起轮椅协调一致上下楼

An inert gas system is designed to reduce the possibility of tank explosions by（）.

A.eliminating sparks and fire in the vicinity of cargo tanks

B.removing all hydrocarbon gases from the cargo tanks

C.blanketing cargo tanks with inert foam

D.reducing the oxygen concentration below levels necessary for combustion