0 the number 1 -- （數字）1
1 a member of a group of people or things -- （一群人或事物）中的一個，之一
EMI is one of the world's largest record companies. EMI公司是世界最大的唱片公司之一。
Finding a cure for cancer is one of the biggest challenges facing medical researchers. 尋找治療癌症的方法是醫學研究者面臨的最大挑戰之一。
Our organization is just one of many charities that are providing famine relief in the region. 我們的組織只是給這個地區提供饑荒救濟的眾多慈善組織之一。
2 used to refer to a time in the future that is not yet decided -- （用於指將來某個未確定的時間）某一
3 used to refer to a particular occasion while avoiding stating the exact moment -- 某一天；某一刻；某一次
4 a single thing; not two or more -- 單獨一個；一個
Eat them one at a time (= separately). 一次吃一個。
I think we should paint the bedroom all one (= in a single) colour. 我覺得我們應該把睡房漆成一種顏色。
UK Do you think five of us will manage to squeeze into the one car? 你覺得我們五個人能夠擠進一輛車嗎？
With this model you get a radio, CD player, and MP3 dock all in one. 這種型號的產品將收音機、CD播放機和MP3轉接底座集於一身。
5 used when saying there is no other person or thing -- 唯一的一個
6 used before the name of someone who is not known -- （用於不認識的人的名字前）某一個
Her solicitor is one John Wintersgill. 她的律師是個名叫約翰‧溫特斯吉爾的人。
8 used to refer to a particular thing or person within a group or range of things or people that are possible or available -- （一群人或一批東西中的）一個
I have a few books on Chinese food. You can borrow one if you want. 我買了幾本關於中國菜的書，如果你喜歡可以借一本。
Which one would you like? 你想要哪一個？
Please make a copy for everybody in the office and a few extra ones for the visitors. 請你給辦公室裡每人印一份，再多印幾份給來訪者。
"Which cake would you like?" "The one in the front." 「你想要哪個蛋糕？」「前面的那個。」
French croissants are so much better than the ones we get here. 法國羊角麵包比我們這裡的好吃得多。
There were lots of people watching, and not one of them offered to help. 有許多人站著旁觀，卻沒有一個人主動幫忙。
I've received no replies to my job applications - not a single one (= none). 我的求職申請沒有任何回覆——一個都沒有。
Chris is the one (= the person) with curly brown hair. 克裡斯就是那個褐色鬈髮的人。
I'm not one to criticize other people, as you know. 你知道，我這人從來不批評人。
I've never been one for staying out late. 我從不喜歡在外逗留到很晚。
9 used to talk about one person or thing compared with other similar or related people or things -- （表示與另一類似或相關的人或物相對照的）一個
They look so similar it's often difficult to distinguish one from the other. 它們看上去這麼相似，常常很難區分開來。
You may have one or the other, but not both. 這個和那個，你可以選一個，但不能都要。
Crime and freedom are inseparable. You can't have one without the other. 犯罪和自由如影隨形，不可能只取其一。
10 any person, but not a particular person -- 任何人；一個人
One has an obligation to one's friends. 任何人對朋友都是負有責任的。
Trouble broke out in the match when one of the players called a member of the other team a cheat.
He can't tell one wine from another, so don't give him any of the expensive stuff.
