问题：
[单选] At the top of the A-frames there is a strong cast iron frame called （）.
cylinder liner。cylinder cover。the gear box。the scavenging box。
问题：
[单选] Be sure to make the engine turn by （） before starting and after stopping .
steering gear。turning gear。steering wheel。turning cycle。
问题：
[单选] Bearing knocks are likely to occur from （）.
less clearance。dirty lube oil。overload。bearing wear。
问题：
[单选] Because the castings of smaller engines are not so big and heavy, （） and cylinder block may be made in one piece.
the column。the jacket。cylinder cover。cylinder liner。
问题：
[单选] Bedplates are the （） of the engine, without the support of which the shaft alignment in particular, and engine structure as a whole, would inevitably be lost.
hull。projection。graphitization。foundatio。
问题：
[单选] Before "stand-by" is rung on the engine telegraph, it is usual to give the main engine （） ahead and astern.
a brief trial with turning gear。a brief trial on power。a long trial by steering gear。one minutes trial with windla。
问题：
[单选] Before a marine diesel engine is started the cylinders and pistons must be （）.
cooled to appropriate temperature。warmed up gradually to appropriate temperature。opened up and renewed。ground and polished。
问题：
[单选] Before being used the fuel service tank should be drained of （）.
soda solution。mechanical impurities。ballast。water and residual。
问题：
[单选] Before pumping up the crankcase oil,（） should be worked by hand to minimize corrosive action on the liners.
the indicators。the starting valves。the cylinder lubricators。the turning gear。
问题：
[单选] Before replacing a piston you should check the rings to see that all clearances and gaps are （） the permissible tolerances.
above。at。over。withi。
