我们参加大大小小的考试，
都要带上一根2B铅笔来涂答题卡。
但是你知道这里的B是什么意思吗?
2B=2 Black
2B铅笔是软性铅笔，
常用于涂抹答题卡和绘画。
这的 B 就是 black，
表示铅笔的黑度。
Pencils are graded using the ‘Graphite Scale’ which measures the softness/hardness of the lead.
铅笔用石墨含量来给铅芯的硬度或者黑度分级。
A pencil lead is made from graphite mixed with clay. Graphite is a naturally soft substance and clay is mixed with it to make it harder. This means a lead with a high graphite content is known as a soft lead and pencils with a soft lead will make a dark mark when used.
铅芯是由石墨和粘土混合制成的。石墨是一种天然的软物质，人们把它和粘土混合在一起使它变硬。这意味着石墨含量高的铅被称为软铅，软铅的铅笔在使用时会留下黑色的痕迹。
Conversely, a lead with less graphite and a higher clay content is known as a hard lead and will make a lighter mark.
相反，石墨少而黏土含量高的铅被称为硬铅，它留下的痕迹较浅。
Soft leads are graded using the letter ‘B’ to designate how ‘black’ the mark they make is. Numbers are then used to indicate the degree of softness - the higher the number the softer the lead and the blacker the mark. For example, a 2B lead is softer than a B lead and will produce a blacker mark. A 4B lead is softer than a 2B etc.
软铅芯用字母B来表示它们黑的程度。然后，数字被用来表示柔软程度——数字越高，铅越软，所以画出来越黑。例如，2B铅比B铅软，会产生更黑的痕迹。4B比2B等要软。
Hard leads are graded in the same way, but use an ‘H’ to show how ‘hard’ they are. A 2H is harder than an H and a 6H is really really hard.
硬铅芯以同样的方式评级，但用H来表示它们有多硬。2H比H硬，6H非常非常硬。
HB (hard black) leads are considered to be the happy medium on the graphite scale. There are no specific industry standards that set down how black HB leads should be, so an HB pencil made by one manufacturer will not necessarily leave the same mark as an HB pencil from a different manufacturer.
硬黑铅被认为是石墨刻度上的理想中值。并没有具体的行业标准来规定HB铅笔芯应该有多黑，所以一个制造商生产的HB铅笔并不一定会和另一个制造商生产的HB铅笔留下相同的痕迹。
相关表达
pen lid 笔帽
sharpen [ˈʃɑːrpən] v. 使变尖;使锋利
sharpen a pencil 削铅笔
pencil sharpener 转笔刀;卷笔刀
我们削铅笔的是想要铅笔的笔芯变得更尖，方便书写，而不是只削掉铅笔的皮，所以削铅笔要说 sharpen a pencil，削铅笔要用的卷笔刀就是 pencil sharpener.
例：
His mother told him to sharpen pencils before the exam.
妈妈叮嘱过他，在考试前削好铅笔。
各种笔的英文表达
eyebrow pencil 眉笔
lip pencil 唇线笔
eyeliner 眼线笔
pencil 铅笔
mechanical pencil 自动铅笔
pen 钢笔
fountain pen 自来水笔
felt-tip [felt tɪp] pen 签字笔
ballpoint pen 圆珠笔
chalk [tʃɑːk] 粉笔
crayon [ˈkreɪən] 蜡笔
Chinese writing brush 毛笔
highlighter [ˈhaɪlaɪtər] 荧光笔
marker [ˈmɑːrkər] 记号笔
paintbrush [ˈpeɪntbrʌʃ] 画笔
END
好啦，今天的小知识点，你学会了嘛？
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