物体质量为，因此有重力，我可以用向量符号，表示这个力。
M the object has a mass m, mg and so there is a force mg, and I can write down the force in vector notation.
高质量的地图符号是丰富地图内容、增强地图的易读性和便于地图编绘的必要前提。
Map symbol with fine quality is the precondition that enrich map content, tone up the legibility of map, convenient for editing of map.
信息技术。自动识别和数据捕获技术。条形码打印质量测试规范。线性符号。
Information technology - Automatic identification and data capture techniques - Bar code print quality test specification - Linear symbols.
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