<ruby id="t5php"></ruby>

        <noframes id="t5php">
        <delect id="t5php"></delect>
        <track id="t5php"></track><cite id="t5php"><video id="t5php"><ol id="t5php"></ol></video></cite>

         
        CN
        You often write with a pencil, but have you noticed the symbols on it?
        Source: | Author:BEST | Publish time: 2020-04-12 | 43 Views | Share:
        You often write with a pencil, but have you noticed the symbols on it? What do they mean?
        You often write with a pencil, but have you noticed the symbols on it? What do they mean?

        Pencil specifications are usually represented by H and B. The symbol H on the pencil means hard, and B means black. "H" is the initial letter of "Hard" in English, which means the hardness of the pencil lead. The larger the number before it, the harder the lead and the lighter the color. "B" is the first letter of "Black" in English, representing the composition of graphite, indicating the softness of the pencil lead and the obvious degree of writing. The larger the number in front of it, the thicker and darker the color.
        AV一本久道久久综合久久鬼色,久久久一本精品99久久精品66,国产精品自在在线午夜,看真人视频A级毛片