单选题The four-stroke engine is used for （） and sometimes for main propulsion with a gearbox to provide a propeller speed of between 90 to 120 rev/min.AalternatorBturbo-chargerCremote controllerDwindlass
单选题
The four-stroke engine is used for （） and sometimes for main propulsion with a gearbox to provide a propeller speed of between 90 to 120 rev/min.
A
alternator
B
turbo-charger
C
remote controller
D
windlass
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