• apocalypse1 (26)in #cn • 4 months ago

  圆珠笔的发展历程

  简单的圆珠笔涉及到的物理原理可不少，它的内部其核心部件是笔尖的金属球，这个直径约1毫米的小球通常由不锈钢、钨合金等材料制成，表面经过精密抛光能在笔尖内腔中自如滚动。…

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• apocalypse1 (26)in #cn • 4 months ago

  How to make yourself better

  First of all, we have to learn self-discipline and defeat procrastination. Daily Goals: Make goals for yourself in…

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