The possibility of damage from operating a diesel engine at critical speeds is reduced by the use of（）.

单项选择题The air supplied to a diesel engine is compressed to （） (1) provide heat for the ignition of the fuel (2) decrease injection delay

A.(1) only is correct
B.(2) only is correct
C.both (1) and (2) are correct
D.neither (1) or (2) are correct

单项选择题In a normally operating diesel engine, the main cause of lubricating oil contamination in the crankcase is a result of the （）.

A.metal particles loosened by wear
B.air when no air cleaners are used
C.condensation of water vapors
D.breakdown of the lubricating oil by dilution

单项选择题The amount of fuel injected in a particular time, or degree, of crankshaft rotation is termed （）.

A.metering
B.timing
C.rate of injection
D.rate of distribution

单项选择题A crankshaft whose center of gravity coincides with its center line is said to be （）.

A.dynamically balanced
B.statically balanced
C.counter balanced
D.resonantly balanced

单项选择题When centrifuging heavy fuel oil, an important factor to consider is the （） (1) flow rate (2) viscosity of the fuel oil

A.(1) only is correct
B.(2) only is correct
C.both (1) and (2) are correct
D.neither (1) or (2) are correct