Advantages: Rubber grip the pedal, lubricant can loose the rusty screw, Roller can help object to move easily, Disadvantages: Rough surface can wear out shoe sole, Amir injured after fall off the bike, Drill produce loud sound and cause sound pollution,

Effect of Frictional Force

排行榜

视觉风格

选项

切换模板

恢复自动保存: