In slow speed two-stroke engines, the fresh air entering begins when and stops as .
A.the inlet port is opened by the up coming piston; the port is closed by the down going
B.the inlet valve is opened by the down going piston; the inlet valve is closed
C.the inlet port is opened by the down going piston; the port is closed by the up coming
D.the inlet valve is opened
第1题
A.scale
B.sludge
C.chemicals
D.air
第2题
A.excessively late fuel injection
B.oil in the air charge
C.water in the fuel
D.injection continuing after the fuel charge is ignited
第3题
A.specific volume
B.density
C.viscosity
D.calorific value
第4题
A.compressor
B.condenser
C.expansion valve
D.evaporator
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