副詞：一次、一度、曾經、以前
常見搭配詞：
- once in a while
偶爾
例句：We eat out once in a while as a special treat.
我們偶爾出去吃飯，犒賞自己(作為一種特殊的享受)。 - once in a blue moon
少有地、千載難逢地
例句：Once in a blue moon she gets some problems.
她偶爾會遇到一些問題。 - once and for all
一勞永逸
例句：We need to solve this problem once and for all.
我們需要一勞永逸地解決這個問題。 - once in a lifetime
一生一次、千載難逢地、難得地
例句：This is a once in a lifetime opportunity, so don’t miss it.
這是千載難逢的機會，所以不要錯過。 - only once
只有一次
例句：I’ve seen that movie only once, but I loved it.
我只看過那部電影一次，但我很喜歡它。 - just this once
就這一次，僅此一回
例句：I’m letting you stay up late, just this once.
我讓你熬夜，就這一次。 - for once
僅此一次、難得一次
例句：For once, you could at least pretend to be happy for me.
就這麼一次，你至少可以假裝為我高興。 - at once
立刻、馬上
例句：We determined to go at once.
我們決定立即出發。 - all at once
突然
例句：All at once, the storm arrived, and we ran for cover.
突然，暴風雨來了，我們趕緊尋找掩護。 - once a week/month/year
每週/每月/每年一次
例句：I go to the gym once a week. 我一週去一次健身房。 - once again (once more)
再次
例句：She proved herself once again by winning the race.
她通過贏得比賽再次證明了自己。 - more than once
不止一次
例句：I’ve warned him more than once about his behavior.
我不止一次警告他的行為。 - once or twice
一兩次
例句：I’ve been there once or twice, but not recently.
我去過那裡一兩次，但最近沒有。 - once upon a time
從前
例句：Once upon a time, there was a hunter living in the forest.
從前，有一個獵人住在森林裡。
例句：
- I have been there once.
我去過那裡一次。 - Once again, he proved that he’s the best in the field.
他再一次證明了他是這個領域最好的。 - I go to the gym once a week to stay fit.
我每週去健身房一次保持身材。 - It only happens like this once in a blue moon.
這種事千載難逢。 - For once in your life, take a risk and follow your dreams.
一生中就一次，冒險一下，追隨你的夢想。 - All at once, I realized what had been bothering me.
突然間，我意識到困擾我的是什麼。 - All at once, the lights went out, and we were in darkness.
突然間，燈熄滅了，我們陷入了黑暗。 - We need to decide once and for all whether we’re moving or not.
我們需要一勞永逸地決定是否搬家。 - She would like to go on a once in a lifetime trip to Antarctica.
她想去南極進行一次終生難忘的旅行 - He was famous once, but now few people remember him.
他曾經很有名，但現在很少人記得他。 - The once wealthy man now lived in poverty.
曾經富有的那個人現在生活貧困。 - Once a cheater, always a cheater.
一次欺騙者，永遠欺騙者。 - Once bitten, twice shy.
一朝被蛇咬，十年怕草繩。 - He wants to travel the world, but he’s never been outside the country even once.
他想環遊世界，但他甚至從未離開過這個國家一次。 - I only met him once at a conference.
我只在一次會議上見過他。 - I only met him once or twice at social events.
我只在社交活動上見過他一兩次。
同義詞：
- formerly 從前、以前 adv. 指的是過去的某個時期或時代。
例句：He was formerly a teacher before becoming a writer.
他以前是老師，後來成為了作家。 - previously 以前、預先 adv. 指的是在特定時間或事件之前。
例句：I had previously met her at a business meeting.
我以前在商業會議上遇到過她。 - one time 一次 – 指的是某事發生的單一次數。
例句：I’ve only been to that city one time.
我只去過那個城市一次。 - at one time 曾經 – 指的是過去的某個時期。
例句：At one time, this building was a school.
曾經，這座建築物是一所學校。 - sometime 某個時候 adv. 指的是不確定的未來時間。
例句：We should meet for coffee sometime.
我們應該找個時間喝咖啡聚聚。
連接詞：一…就、一旦…就
例句：
- Once you’ve tried it, you’ll never want to eat anything else.
你一旦嘗試過它，就再也不想吃其他東西了。 - Once the meeting is over, I’ll give you a call.
會議一結束，我就給你打電話。 - Once you understand the basics, the rest becomes easier.
一旦你理解了基礎知識，其餘的就變得更容易了。 - He’ll arrive once the train gets in.
火車一到，他就會到達。 - Once the contract is signed, we can begin the work.
一旦合同簽署，我們就可以開始工作。
同義詞：
- as soon as 一…就，表示某件事接著另一件事發生。
例句：As soon as he arrived, the party began.
他一到，派對就開始了。 - when 當…時候，用於表示一個事件與另一個事件同時或相繼發生。
例句：I’ll call you when I get home.
我到家時會給你打電話。 - after 在…之後，用來表示一個動作或事件跟在另一個之後發生。
例句：After the rain stopped, we went outside.
雨停後，我們走到外面。 - immediately 立刻，用於表示一個事件接著另一個事件發生，無需等待。
例句：She left the room immediately after the meeting.
會議後，她立刻離開了房間。 - the moment 此刻，表示某事在某一特定時刻發生。
例句：I knew it was a mistake the moment I said it.
我說出口的那一刻就知道那是個錯誤。
衍生字：
- once-in-a-lifetime 一生中難得一次、千載難逢的、難能可貴的 adj.
