Lu Ban (lǔ bān 魯班) was supposed to be a consummate carpenter in ancient times. It is said that he once carved a wooden phoenix that was so lifelike that it actually flew in the sky for three days. Thus it was considered the height of folly to show off one's skill with an axe in front of Lu Ban.

古代有一個建筑和雕刻技術非常高超的人，名叫魯班，他是一個善于制作精巧器具的能手，木匠行里尊稱他為祖師。傳說他曾用木頭制作了一只五彩斑斕的鳳凰，能夠在空中飛翔三天不掉下來。誰敢在魯班門前賣弄使用斧子的技術，也就是說，想在大行家面前顯示自的本領，這種太不謙虛的可笑行為，就叫做“魯班門前弄大斧”，簡稱“班門弄斧”。 這句成語有時也用作自謙之詞，表示自己不敢在行家面前賣弄自己的小本領。

班門弄斧 (bān mén nòng fǔ)
【翻譯】Showing Off One's Proficiency with the Axe Before Lu Ban the Master Carpenter.
【釋義】在魯班門前舞弄斧子。比喻在行家面前賣弄本領，不自量力。
【例句】姐姐學問淵博，妹妹不敢班門弄斧，亂加評論。
【近義詞】布鼓雷門，貽笑大方
【反義詞】虛懷若谷，自知之明，知人之明　

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