Combustion knock occurring in a diesel engine can be caused by （）.

[单选题]C．ombustion knock occurring in a diesel engine can be caused by _____.A．low coolant temperatureB．insufficient fuelC．high ambient temperatureD．carbon buildup on the injector tips

[单选题]Combustion knock can occur in the cylinders of a diesel engine under any condition permitting （）.A . a shortened ignition delay periodB . a lean fuel/air mixtureC . excess fuel in the combustion chamberD . rapid vaporization of injected fuel droplet

[单选题]A diesel engine with a combustion chamber located between the crowns of two pistons is known as a/an （）.A . double-acting engineB . opposed pistons engineC . single-acting engineD . horizontal acting engine

[单选题]Diesel engines obtain combustion air through turbo chargers，blowers，or（）.A . air startersB . carburetorsC . natural aspirationD . air receiver

[单选题]Poor combustion in a diesel engine can be caused by （）.A . high compression pressureB . low intake air temperatureC . low exhaust pressureD . high scavenge air pressure

[单选题]The color of the exhaust from a diesel engine should be （）A . clearB . hazy light brownC . hazy light blueD . hazy light grey

[单选题]The rate of fuel injection in a diesel engine cylinder depends primarily on （）.A . the size of the holes in the fuel nozzleB . timing of the pumpC . supply pressure to the pumpD . shape of the combustion chamber

[单选题]Before starting any diesel or gasoline engine，which of the following must be checked? （）A . Oil levelB . Flow of cooling waterC . Exhaust dischargeD . All of the above

[单选题]To avoid scavenge fires occurring the engine timing and equipment maintenance （）.A . should be correctly carried outB . should correctly be taken placeC . should carded with careD . must to carry out with great care

[名词解释] knock out（基因敲除）