If you must make an electricity connection in a poorly accessible spot, solder it and seal it against （）

A、metal

B、wood

C、water

D、plastic

Emergency generator is installed on board mainly to （）

A、connect to the busbar when the load increasing

B、supply power specially to charging panel

C、be put into operation during the ship arriving at or leaving port

D、ensure the power supply to critical equipment after the main switchboard out of power

A leaking diesel engine fuel injector will cause（）

A、prolonged maintenance intervals

B、improved atomization

C、greater fuel economy

D、incomplete combustion

The pressure range between the system cut in and cut out pressures in a refrigeration unit is known as（）

A、opposing operational drag

B、pressure distribution

C、differential

D、system purge

（）, the motion would continue indefinitely once it had started.

A、Were there loss of energy by friction

B、Since there be loss of energy by friction

C、Were there no loss of energy by friction

D、Should be no loss of energy by friction

（） that everything in the engine crankcase is correct, start up the crankcase lubricating oil pump.

A、To satisfy

B、To be satisfied

C、After satisfying

D、After being satisfied