单项选择题 If a four-stroke/cycle diesel engine is running at 1550 RPM, the speed of the camshaft will be（）.

单项选择题 An indication of a diesel engine air intake being partially clogged, is （）.

单项选择题 The closing of the exhaust valves used on a modern, large, low-speed, main propulsion diesel engine may be directly provided by （）.