单项选择题
A diesel engine which is rated for normal operation at a crankshaft speed of 800 RPM, is commonly classed as a （）.
A.slow-speed diesel B.medium-speed diesel C.high-speed diesel D.constant-speed diesel
单项选择题 The three basic parts of any eductor are the nozzle, the suction chamber, and the （）.
单项选择题 （）, the engine must be stopped immediately.
单项选择题 Grind the （）.
