单项选择题 （）does not belong to the mooring trial item.

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 （）