单项选择题
A.generator sets running trial
B.shafting intensity trial
C.the trail for pumps that working for ME
D.ME safety devices trial
单项选择题 According to the regulation of the voyage trial on new ship,（）is one of the trial items of the UMS ship bridge control.
单项选择题 During the dock repair, each sea valve must be disassembled, cleaned and ground well.Before it reassemble the sealing surface between the valve and the valve seat should be checked by （）
单项选择题 During the dock repair, when installing the tail shaft and propeller, who should be on the spot to supervise?（）