單項(xiàng)選擇題

The exhaust valve opens before bottom dead center in a four stroke engine to（）
Ⅰ.allow for blow down
Ⅱ.Reduce pumping losses

A.Ⅰ only
B.Ⅱ only
C.both Ⅰ and Ⅱ
D.neither Ⅰ nor Ⅱ


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A.Constant volume
B.Constant pressure
C.Pulse pressure
D.Radial flow

2.單項(xiàng)選擇題Which of the following conditions indicates the dilution of diesel engine lube oil by fuel oil?（）

A.Water discharging from the water outlet of the lube oil purifier
B.Fuel oil discharging from the water outlet of the lube oil purifier
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D.A change in the lube oil viscosity

3.單項(xiàng)選擇題If a single cylinder relief valve on a diesel engine lists frequently while the engine is running, the cause may be an （）

A.excessively late injection timing for each cylinder
B.incorrectly adjusted intake valve timing
C.incorrectly adjusted fuel injector
D.incorrectly adjusted intake valve clearance

4.單項(xiàng)選擇題Which of the diesel engine cylinder liners listed has internal cooling water passages?（）

A.Internally finned liner
B.Externally finned liner
C.Wet liner
D.Integral water-jacket liner

5.單項(xiàng)選擇題Diesel engine lube oil can become contaminated as a result（）

A.the water produced during combustion
B.the sulfur in the fuel
C.unburned fuel oil
D.all of the above