Pipe smokers sometimes wear down the tips of their teeth where they grip their pipes.抽烟斗的人用牙齿咬住烟斗，有时会把齿尖磨平。The machines start to wear down, they don't make as many nuts and bolts as they used to.机器开始出现磨损，螺母和螺钉的产量不如从前了。They hoped the waiting and the uncertainty would wear down my resistance.他们希望拖延搁置会瓦解我的抵抗。