单项选择题 Cavitation erosion in the cooling water system of a diesel engine usually occurs at the pump impeller, and on the waterside of the （）

单项选择题 Which of the following factors tends to increase scale formation on the saltwater side of a heat exchanger used in a diesel engine cooling water system?（）

单项选择题 Gear-type flexible couplings are often used in diesel engine drive trains because they（）