单项选择题
A.Keeps the refrigerated space cooler
B.Reduces the efficiency of the plant
C.Takes the load off the compressor
D.Has no affect on the system
单项选择题 When the vessels steering wheel on the navigation bridge is turned, the difference existing between the position of the wheel and that of the rudder is known as （）.
单项选择题 Which of the listed statements is correct concerning refrigeration systems?（）
单项选择题 By which of the following means is force efficiently provided to vary the pitch of the blades on a modem controllable pitch propeller?（）