A controllable pitch propeller on a diesel driven vessel eliminates the need for
A. friction clutches
B. disconnect clutches
C. reversing gears
D. reduction gears
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如果某人在树下埋了一罐货币，那么货币的职能是________。
A. 交易媒介
B. 计价单位
C. 支付手段
D. 价值储藏
E. 实物交易工具
Diesel engines are started by supplying_____into the cylinders in the appropriate sequence
A. cooling water
B. compressing air
C. compressed air
D. cylinder oil
One of the most common causes of reduction gear failure is gear wear caused by scoring as
A. surface fatigue of the gears
B. an inadequate lube oil film
C. plastic flow of the gears
D. fretting corrosion from water
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