Poor tooth brushing techniques can harm your teeth - if you really scrub your teeth too hard, you will wear the sides of your teeth down, leaving V-shaped defects near the gum margins.
不恰当的刷牙方法会损害牙齿，如果你真的太用力刷牙，就会磨损牙齿边缘，在牙龈缘附近形成V字形缺口。
Under a wide range of P and V value, there are very low friction coefficient and wear, high dimensional stability for coating-metal pairs and no any damage during the test of nylon coating.
涂层在较大的P、V值范围内与各类配副均具有极低的摩擦系数和磨损量以及很高的尺寸稳定性；长期工作过程中，涂层未出现任何破坏现象。
The results show that the wear resistance can be improved by using fine particle, even and high content of V in the alloy.
研究结果表明：合金中V颗粒细小且弥散均匀以及提高V的含量，有利于提高合金材料的耐磨损性能；
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