基本供水方式可分为( )四种。

A．分质供水方式

B．直接供水方式

C．水泵水箱的供水方式

D．设置水箱的供水方式

E．分区分压供水方式

If your vessel is underway in fog and you hear one prolonged and three short blasts，this indicates a（）.

A.vessel not under command

B.sailing vessel

C.vessel in distress

D.vessel being towed