lowerleg足loweradj.低的；下级的；下层的v.降低；减弱；跌落lower-class culture下层阶级文化Lower limb shortening下肢短缩lower lateral bracing纵向下平联Lower-effect forest低效林lower forms of animal低等动物lower level interrupt低级中断lower flammable limit易燃下限lower calorific power低卡值lower low water datum低低潮基准面lower grade limestone低品位石灰石

1. It is suitable for small and medium vessels with upper and lower rudder constructions.
   适用于使用上下舵承结构的中小型船舶。