When learning computer programming, I found it helpful to look at a function like a pencil sharpener. A parameter was a dull pencil, inside processes sharpened and returned a sharp pencil.

我在学编程时，常把程序比作卷笔刀，而把参数比作钝铅笔，经过处理我们就得到尖铅笔了。

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Suddenly there were swords everywhere: fat swords, skinny swords, sharp swords, dull swords, fancy swords, but mostly tiny swords so that one man might carry many of them.

商人们忙碌了起来，一时间到处都是卖剑的，剑身有宽有窄，剑刃或利或钝，亦有的宝剑花哨夺目，卖得最多的是袖珍的宝剑，唯有这样一个人才能佩戴很多把。

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The discomfort may be sharp or a dull ache that gets worse towards the end of the day.

疼痛的感觉可能是剧烈而快速的，也可能是持续恶化的很久的钝痛。

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Sooner or later, their once-sharp skills get dull, and they ride on past performance.

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These early tools closely resembled the knives we use today, consisting of a piece of metal that was sharp on one end--the blade--and dull on the other--the tang.

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