单项选择题
A diesel engine is operating at 1800 RPM and driving a propeller at 600 RPMWhat is the speed reduction ratio?（）
A.030 to 1 B.300 to 1 C.333 to 1 D.330 to 1
单项选择题 High diesel engine cooling water temperatures can be caused by （）.
单项选择题 The rotary motion of a diesel engine crankshaft is obtained from the up and down motion of the piston via the （）.
