目前使用的锯条的锯齿角度是如何分配的？锯条反装后锯齿角度有何变化？
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郑州地铁一期工程在主变电站油变压器房设置有自动水喷雾灭火系统。
A. 正确
B. 错误
Typical marine propulsion plants include（） directly coupled to the vessel’s single large-diameter, fixed-pitch propeller.
A. a single, long-stroke, slow-speed, turbocharged, two-stroke diesel engine
B. a single, long-stroke, medium-speed, turbocharged, four-stroke diesel engine
C. two medium-speed, turbocharged, four-stroke diesel engines
D. a variable-speed AC generator
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