单项选择题
Critical speed in diesel engines occurs when engine torque pulsations become （）
A.opposed to the crankshaft rocking couple B.resonant with the crankshaft natural frequency C.critical fore and aft crankshaft vibrations D.horizontal whipping motions of the crankshaft
单项选择题 Air receivers installed in starting air systems are to be （）.
单项选择题 Which of the conditions listed may occur in an operating diesel engine if air pockets form within the cylinder head circulating water passages? （）
单项选择题 The two strokes of a two-stroke/cycle diesel engine are （）
