基本解释曲柄回转力英汉例句双语例句By focusing on staying narrow, you'll reduce your surface area, and crank faster with less effort.集中注意力保持夹紧状态，你会减小表面积，从而以更少的力气游得更快。词组短语短语crank effort diagram 曲柄回转力图专业释义机械工程曲柄回转力