【成語來源】?

be an expert in
一技之長(zhǎng)

Gong sun Long (公孫龍), a famous scholar lived in the State of Zhao (趙國(guó)) during the Warring States Period (戰(zhàn)國(guó),475――221BC), had a habit of maintaining a great number of skilled people around him.
戰(zhàn)國(guó)時(shí)期，趙國(guó)有位名士叫公孫龍。他手下聚集了許多有自己特長(zhǎng)的門客。

He often said, "A wise man should welcome anyone with a specialty."
他常說：“一個(gè)聰明人應(yīng)該善于接納每一個(gè)有自己特長(zhǎng)的人?！?

One day, a man in shabby clothes came to see him and said to him:" I have a special skill. " Gong asked: "What is it?""I have a loud voice and I'm good at shouting."
有一天，有個(gè)穿著很破爛的人來見他，并向他推薦自己：“我有一項(xiàng)特別的本領(lǐng)?！惫珜O龍就問道：“什么本領(lǐng)？”那個(gè)人回答道：“我聲音特別大，很善于叫喊。”

Then Gong turned to his followers and asked," Who is good at shouting?" But none of them answered "Yes ". So the scholar took the man in.
公孫龍聽了，就轉(zhuǎn)身問他旁邊的門客：“你們有誰善于叫喊？”結(jié)果沒有一個(gè)人回答“是”。于是，他就收下了這個(gè)很善于叫的人作他的隨從。

Some days later, Gong and his followers went on a trip.
沒過多久，公孫龍和他的門客一起出外游玩。

They came to a wide river and found the boat was on the other side of the river. All of them had no idea. Suddenly, Gong thought of the shouting expert and turned to him, "Can you have a try?"?
他們來到一條很寬的河邊，發(fā)現(xiàn)渡船在河的另一頭，所有人都不知怎么辦好。突然，公孫龍想起他最近收的那個(gè)人的本領(lǐng)是善于叫，于是，他就轉(zhuǎn)過頭去對(duì)那人說：“你大聲叫對(duì)面的船夫，看能不能把他叫過來?！?/div>

The man realized it was the chance to show his skill. He shouted to the ferryman as loud as he could, "Hey, ferryman, come here, we want to cross the river." As his voice ended, the ferryman came to fetch them. Gong was very satisfied with the new follower.
那人覺得展示他技能的時(shí)候到了，就盡力大聲向?qū)γ婧埃骸拔?，船夫，過來，我們要過河?！碑?dāng)他叫聲剛完，那對(duì)面的船夫就搖著船過來了。公孫龍對(duì)這個(gè)新收的門客非常滿意。

Later, people use it to describe anyone who has a special professional skill.
后來，“一技之長(zhǎng)”就用來形容一個(gè)人有一項(xiàng)特殊的本領(lǐng)。

【文化鏈接】

英文中“一技之長(zhǎng)”可以用“be expert in”來表達(dá)，直譯也就是“哪一方面的專家”的意思，這樣一想也就容易理解了~
我們來看個(gè)例句：

How to become an expert in your field?
如何成為你的領(lǐng)域的專家？/如何擁有一技之長(zhǎng)？