translation.en: People have been struggling for years to try and design a very fast rotating boat propeller that doesn't cavitate and literally wear away the metal and put holes in it, just like these pictures show.
translation.zh: 人们已花了很多年的时间在不懈的尝试和设计 一种非常快速的旋转螺旋辊，那种没有空化 并且不会磨损和对金属桨穿洞 就像这些图片所展示的。