1. True change, true forward motion, takes many small changes, minute by minute. 真正的变化,真正向前的举动包含一点一滴的小变化。
2. By its rotation in water or air, the propeller produces thrust on the Blades, which gives forward motion to the vehicle . 当它在水中或空气中旋转时就对桨叶产生推力,然后推动交通工具前进。
3. A hinged or pivoted device adapted to fit into a notch of a ratchet wheel to impart forward motion or prevent backward motion. 掣爪,''。'棘'。''爪一种枢''。'轴'。''或转''。'轴'。''器械,能与齿轮缺口或齿间吻合来前进或防止后移。