问题：
[单选] The machine has stopped rotating because the bearing （） the shaft.
seized。clogged。melted。inserted。
问题：
[单选] The main bearing metal is a lining （）.
inside the bearing。outside the bearing。covering the crankshaft。none of the above。
问题：
[单选] The main bearing shells are made of steel with a lining of bearing metal which may be white metal, copper-lead or aluminum-tin alloy What is the meaning of “which” in the sentence above?（）
main bearing shells。main bearing。steel。bearing metal。
问题：
[单选] The main bearing shells often have a thin （） of lead or indium to provide a layer giving protection against corrosion.
flange。flash。plate。sheet。
问题：
[单选] The main bearings are provided with thin-walled （）, lined with a copper-lead alloy.
steel guides。steel shells。steel bearing caps。pig iro。
问题：
[单选] The main factor which determines the output of each cylinder is （）
the cylinder weight。the cylinder bore。the cylinder length。the cylinder cover。
问题：
[单选] The main function of the lubrication system in to enable （） of a film of oil between the moving parts.
the information。the formation。the scatter。the frictio。
问题：
[单选] The main moving parts of a diesel engine consist of the （） and the pistons.
bedplate, connecting rods。crankshaft, the connecting rods。frames, crossheads。crankshaft, the cylinder。
问题：
[单选] The majority of medium speed and high speed marine diesel engines for main or auxiliary drive operate on the （） cycle.
two-stroke。four-stoke。long-stroke。short-stroke。
问题：
[单选] The marine diesel engine is a type of diesel engine used on ships The （） of its operation is not very difficult to understand.
principle。principal。cause。case。
