单项选择题
A.above normal with a below normal exhaust temperature
B.above normal with a normal exhaust temperature
C.below normal with a normal exhaust temperature
D.below normal with an above normal exhaust temperature
单项选择题 Critical speeds occurring within the operating speed range of a main propulsion diesel engine may be changed, or have their damaging effects reduced by a/an （）
单项选择题 Performance of a turbocharged engine can be improved by（）
单项选择题 Which of the devices listed is installed on a diesel engine to isolate some of the crankshaft vibrations caused by rotational and reciprocating forces?（）