一个民族要生存和发展，就要有昂扬向上的民族精神。民族精神是民族文化的

A．精髓

B．灵魂

C．实质

D．核心

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