中央信号装置包括事故信号装置和预告信号装置两种。

If more than one raft is manned after the vessel has sunk，you should（）.

A.go in a different direction in search of land

B.spread out to increase the possibility of a search aircraft finding you

C.reduce the number of rafts by getting as many people as possible into as few rafts as possible

D.tie the rafts together and try to stay in a single group