In four strokes engine, the cycle of e

1、In a four-stroke engine the camshaft r

In a four-stroke engine the camshaft rotates at （）.Ahalf the engine speedBtwice the engine speedCthe engine speedDfour times the engine speed

2、In a four-stroke cycle diesel engine t

In a four-stroke cycle diesel engine the intake valves open （）Abefore TDC and close after BDCBafter TDC and close after BDCCbefore TDC and close before BDCDafter TDC and close before BDC

3、Scavenging in a four-stroke/cycle dies

Scavenging in a four-stroke/cycle diesel engine occurs during the （）.Alast part of the exhaust stroke, and the first part of the intake strokeBlast part of the intake stroke onlyCearly part of the injection stroke onlyDearly part of the power stroke

4、In a single acting, four-stroke/cycle

In a single acting, four-stroke/cycle diesel engine, the power impulse in an individual cylinder occurs （）Aonce every crankshaft revolutionBonce every two crankshaft revolutionsConce every piston strokeDtwice every piston stroke

5、If a four-stroke/cycle diesel engine i

If a four-stroke/cycle diesel engine is started by injecting air into the cylinder, the pistons receiving the charge of starting air must be（）Aon the power strokeBon the exhaust strokeCat the end of the power strokeDat the start of the intake stroke

6、In the four-stroke engine, it takes （）

In the four-stroke engine, it takes （） to make one power stroke.Aone propulsionBtwo propulsionsCtwo revolutionsDone revolutio