单项选择题
A.closing later
B.opening sooner
C.staying open for a shorter period of time
D.staying open for a longer period of time
单项选择题 A diesel engine crankcase ventilation system （）
单项选择题 Regarding a Diesel engine crankcase, the general arrangement and installation should preclude the possibility of （）
单项选择题 If the valve tappets in a diesel engine are set at greater clearances than those specified by the engine manufacturer, those valves will （）