单项选择题
（）with various arrangements of barrels are the usual mooring equipment used on board ships.
A.cranes
B.winches
C.capstans
D.windlass
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相关考题
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单项选择题
In order to culture and propagate enough bacteria to treat the body and galley wastes（）
A.a new bacteria colony should be put into the plant in advance
B.the disinfection chemicals should be always used
C.the air blower should be started and keep running in advance
D.the nutrient for bacteria should put into plant in advance -
单项选择题
（）are used to digest the sewage to produce innocuous sludge in a biological sewage treatment plant.
A.anaerobic bacteria
B.aerobic bacteria
C.air bubbles
D.disinfection chemicals -
单项选择题
The extended aeration process consists of （） the liquor either by bubbling air through it or by agitating the surface.
A.deoxygenating
B.oxygenating
C.chemicalizing
D.disinfecting
