Each time we use a facial muscle, a groove forms beneath the surface of the skin, which is why we see lines form with each facial expression.

每当你使用面部肌肉的时候，皮肤下就会形成一道凹槽，这就是你作表情的时候，脸部出现线条的原因。

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The savage on the shores of the Pacific cuts a groove in the bark round the root of the tree of which he intends to form his canoe.

太平洋岸边的野人绕着一个树根挖槽，想用这棵树建造一艘独木舟。

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Two groove of the inner ring and outer ring groove for the ball between the form of a drum, equipped with roller bearings.

二条滚道的内圈和滚道为球面的外圈之间，装配有鼓形滚子的轴承。

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