单项选择题
A.in order to B.because of C.so that D.so as to
The film of oil between the rings and the liner is not ...
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
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
The figure that the volume of air at BDC is divided by ...
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
