并能正确标注尺寸及加工表面符号，公差与配合。

Learning to mark dimensions, manufacturing surface symbols tolerance and fittings correctly.

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零件尺寸的两个极限之差称为公差，这是一个没有符号的绝对量值。

The difference between the two limits of size of a part is called the tolerance, an absolute amount without sign.

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当具有公差要求的被测要素为线或平面时，将指引线箭头和基准符号指在线或平面上，且必须与尺寸线错开。

If the element being tested with a tolerance requirement is a contour line or surface, point the arrow and datum symbol to the contour line or surface, and keep it away from the dimension line.

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