In an automatic mooring winches, the wire is paid off the barrel at（） a tension and is recovered at（）tension.

单项选择题When the power is shut off, the wire（）

A.becomes slack
B.can not be paid out unless the brake is overhauled or recover wire unless manually operated
C.will be let out because the brake is out of work
D.may be pay out due to no power

单项选择题For a flash type evaporator, a demister is located the condenser（）

A.After
B.before
C.inside
D.outside

单项选择题For a flash type evaporator, the seawater heater will have to maintain a enough temperature to minimize scale formation（）

A.lower
B.higher
C.low
D.high

单项选择题The flash-evaporator is different with the submerged-tube evaporator in that for the former（）

A.Water is heated into vapor on heating surfaces
B.Water is vaporized by pressure difference
C.There are no heating-transfer surfaces
D.There are more heating-transfer surfaces

单项选择题Which one of the followings might not be employed to create vacuum for flash type evaporator? （）

A.high-pressure steam-driven air-ejector
B.motor-driven vacuum pump
C.water-motivated air eductor
D.centrifuge pump