单项选择题
Before starting an engine by air, the engine must（）
A.be turned by a turning gear for at least one minute B.be turned by a turning gear for at least two minutes C.be turned at least one complete turn D.be turned at least two complete turns
单项选择题 The oil pressure and flow from each bearings can be checked when（）
单项选择题 When preparing an engine for water temperature（）
单项选择题 When stand-by engine instructions have been received, it’s necessary to make it sure that all valves in the various systems are（）
