单项选择题
A.suction B.compression C.expansion D.exhaust
The fine filters will be arranged （） one can be cleaned...
单项选择题The fine filters will be arranged （） one can be cleaned while the other is operating.
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
