1. Number one 最重要的人(或事物);最好的人(或事物)

Many people consider themselves number one, the most important person.

很多人認為他們自己就是最好的，是最重要的一個人。

2. Look out for/ Take care of number one 先為自己著想，照顧自己的利益, 為自己打算

One and only 絕無僅有的;獨一無二的;有名的

They are always looking out for number one and taking care of number one. It is as if they are the one and only person on Earth.

他們總是先為自己著想，只關心自己的利益，就好像他們是地球上唯一的人。

3. Pull a fast one 欺騙, 搗鬼

Jim only won the game because he pulled a fast one on his opponent.

吉姆因為跟對手耍了手段，才贏了比賽。

4. One in a million百萬分之一，鳳毛麟角，百里挑一，佼佼者

She’s one in a million.

她是個百里挑一的人。

5. At one time 同時, 曾經

At one time we met frequently.

我們過去常見面。

6. Roll up into one 合為一體;兼于一身

She is a great person -- kind, thoughtful and intelligent -- all good qualities rolled up into one.

她是個很優秀的女人——善良，體貼，聰慧——集所有可貴品質于一身。

7. One good turn deserves another. 善須善報;要以德報德;好人應得好報。

If he does you a favor, you should do him a favor. One good turn deserves another.

如果他幫你的忙，那么你就應幫他的忙，以德報德嘛。

8. Be/go back to square one 退回起點, 從頭再來

His papers were lost in the accident, so he had to go back to square one with the work.

他的論文在這次事故中弄丟了，只得從頭再寫。