单项选择题
Dual electro-hydraulic steering units usually operate （）.
A.with both pumps on line at the same time
B.with one pump on standby
C.with the follow-up gear disconnected
D.only when the rudder is moved amidships
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相关考题
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单项选择题
One distinct advantage of flash type evaporators, as compared to most other evaporators, is that in a flash evaporator （）.
A.high temperature distillate can be re- circulated to induce additional flashing
B.scale formation is not a severe problem
C.cold shocking is more effective in removing scale
D.water purity is greatly increased at high capacity -
单项选择题
A liquid indicator sight glass is useful in determining whether or not a refrigeration system is sufficiently chargedIt is generally located in the（）.
A.high pressure liquid line
B.low pressure liquid line
C.high pressure vapor line
D.low pressure vapor line -
单项选择题
Compared to a constant pitch propeller, a controllable pitch propeller（）.
A.more efficiently uses available engine power
B.operates at a lower efficiency at a fixed speed
C.produces the same torque at lower engine power
D.develops its rated power at a lower speed
