单项选择题
What is the principle behind dynamic braking as used on an anchor windlass?（）
A.Electrical loading B.Mechanical distribution C.Compressibility of air D.Mechanical friction
单项选择题 What is the holding power ratio of an anchor? （）
单项选择题 What is the function of wearing rings found on some centrifugal pumps? （）
单项选择题 What is the best indication of the loading of a diesel engine?（）
