单项选择题
Which of the devices listed, when used on an electro-hydraulic steering gear, keeps the movement of the redder closely in step with the steering wheel?（）
A.The follow-up gear B.The rudder angle indicator C.The synchronous electric transmitter D.A rudder angle limit switch
单项选择题 Propeller pitch speed minus ship speed divided by the propeller pitch speed is termed （）.
单项选择题 A multistage centrifugal pump can be BEST described as having （）.
单项选择题 If a refrigeration system compressor crankcase is sweating, you should （）.
