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?（）

A.chief engineer
B.the engineer
C.captain
D.any member of the engine department

单项选择题When the vessel entering the dock, the first work that engineer should contact with the shipyard （）

A.releasing the boiler water
B.the explosion detecting and cleaning for the fuel tank
C.the docking project related item
D.shore power and fire fighting water supply

单项选择题When the dock is refilled with water after docking repair, the first work which should be done by engineers is （）

A.igniting boiler
B.releasing air in sea water system
C.starting generator
D.cut off shore power

单项选择题During the deck repair,（） should be measured firstly before tail shaft is drawn out.

A.the sinking of tail shaft
B.the clearance of stern bearing
C.the total flexure of both end bearing
D.main engine crankshaft deflection

单项选择题To ensure the quality of dock repair, C E should know very well （）

A.the repair standard of main docking repair item
B.the special tool for repair item
C.the skill of repairer
D.the status of docking repair equipment