单项选择题
The film of oil between the rings and the liner is not only essential for the lubrication but also （） achieving a gas seal.
A.play a great part on
B.run a role in
C.plays an important part in
D.acts as important part at
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相关考题
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单项选择题
The film of oil between the rings and the liner is not only essential for the lubrication but also plays an important part in achieving （）.
A.an oil seal
B.removing heat
C.a gas seal
D.cooling the piston -
单项选择题
The figure that the volume of air at BDC is divided by the volume of air at TDC is termed as（）.
A.ignition ratio
B.power ratio
C.compression ratio
D.injection ratio -
单项选择题
The external circumference of a pair of main bearing shells is slightly larger than that of the bore of the housing which receives themThe difference is termed （）.
A.nip
B.nap
C.gap
D.lip
