单项选择题
The discharge head of a centrifugal pump will vary directly with the （）.
A.change in impeller diameter B.square of the impeller diameter C.cube of the impeller diameter D.impeller efficiency for large changes in the size of the impeller
单项选择题 An increase in the heat load to a refrigeration system will cause （）.
单项选择题 Which of the following types of hydraulic pumps would be used in a steering system?（）
单项选择题 Which of the following statements is true concerning centrifugal pumps?（）
