化油器按喉管处空气流动方向的不同，可分为上吸式、（）和下吸式三种。 ["单喉管式","双重喉管式","中吸式","平吸式"]
Permission is kindly （） about 1000 tons of clean sea water ballast，as and when required for trimming purposes． ["requested to pump out","requested pumping out","requesting to pump out","requesting pumping out"]
“Stand by engine” means （）. ["prepare to stop the engine","assemble an engine on its bedplate","make an engine ready for starting","make an engine run steadily"]
痕量元素表面富集理论
在船舶倾斜20°一舷放艇首先应该采取的措施是（）。 ["先在艇首、尾中设滑撬、便于艇的降放","先在艇首尾与船舶之间系上拉紧索、便于人员登艇","先使用钩篙抵撑、扩大艇与船之间的距离"]
无线调度命令传送系统为含（）、（）、调车作业通知单、列车接车进路预告信息的无线传送系统。
