（）是收益还原法和剩余法估价的基础。

A.替代原则

B.贡献原则

C.预期收益原则

D.报酬递增递减原则

Prior to entering a davit-launched liferaft，you should make sure that（）.

A.the liferaft is well ventilated of excess carbon dioxide

B.all personnel have removed their life preservers to facilitate boarding

C.the door flap has been cut away and stowed inside the raft

D.All of the above