单项选择题 A bronze bearing liner with a lead-tin flashing has a milky-white color over most of its surface and some areas of exposed bronze, the white coloring indicates（）

单项选择题 If a diesel engine turned over freely but failed to start, the cause could be （）

单项选择题 If it becomes necessary to cutout an individual cylinder of a large, low-speed, main propulsion diesel engine, the fuel to that cylinder should be secured and its （）