1. at or during the time that
在…的時候；當…時
I was reading a book when the phone rang.
電話響的時候，我正在看書。
Call me when you arrive at the station.
你到車站的時候打給我。
When Meaning（定義、用法、例句與發音）
when
conjunction
快速理解
What does "When" mean?What are 2-3 core uses of "When"?
用於詢問或指涉某個特定的時間點或事件發生的時刻。
- 1
詢問時間
EN: At what time?
翻譯: 在什麼時候？
- 2
指特定時間
EN: At the time that something happens.
翻譯: 指某事發生的那個時刻。
- 3
表示條件
EN: If or considering that.
翻譯: 表示如果或考慮到某種情況。
- 4
表示對比
EN: Whereas or although.
翻譯: 表示然而或雖然。
小提醒：注意 'when' 引導的從句，若主句是未來式，從句通常用現在式表示未來時間，例如：'I will call you when I arrive.' (不是 'when I will arrive')。
發音（How to Pronounce "When" in English）
How to pronounce "When" in English?"When" US vs UK pronunciation
點擊下方的 US / UK 按鈕可播放發音。
Real-life Examples of "When" from YouTube Videos
South Korea would accept Trump-Kim deal to freeze North Korea’s nuclear programme | BBC News
BBC News
“How do you justify turning these off at a time when the UN has just found that North Koreans are more isolated than they've ever been?”
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Definitions（定義）
What are the definitions of "When"?How does "When" change by context?
2. after which; and then
然後；之後
She finished her work, when she went out for a walk.
她完成工作後，就出去散步了。
We'll have dinner first, when we can decide what to do next.
我們先吃晚餐，然後再決定接下來要做什麼。
3. considering that; although
考慮到；雖然
Why do you complain about the weather when you could stay indoors?
既然你可以待在室內，為什麼還要抱怨天氣呢？
It seems strange that he left when he had just arrived.
他剛到就離開，這似乎很奇怪。
4. used to introduce a question about time
（用於詢問時間）何時
When are you coming to visit?
你什麼時候要來拜訪？
Do you know when the meeting starts?
你知道會議什麼時候開始嗎？
5. if; in the event that
如果；萬一
When you see him, please give him this message.
如果你見到他，請把這個訊息轉告他。
How can we finish the project when we don't have enough staff?
如果我們人手不足，要怎麼完成這個專案？
Grammar & Patterns（句型）
What are common sentence patterns for "When"?How to make natural sentences with "When"?
| Pattern | Meaning | Example |
|---|---|---|
| when + clause | 當…的時候 | When I arrived, the meeting had already started. (當我抵達時，會議已經開始了。) |
| clause + when + clause | …，當…的時候 | I was reading a book when the phone rang. (我正在看書，這時電話響了。) |
| when + noun phrase | 在…的時候 | When a child, he lived in the countryside. (小時候，他住在鄉下。) |
| Hardly/Scarcely + had + subject + past participle + when + clause | 剛…就… | Hardly had I closed my eyes when I fell asleep. (我剛閉上眼睛就睡著了。) |
| since when + question | 從何時開始… | Since when have you been interested in classical music? (你是從什麼時候開始對古典音樂感興趣的？) |
用法說明
How is "When" different from similar structures?What usage mistakes are common with "When"?
when doing vs when to do
- when doing 用於描述一個動作發生的「時間點」或「情境」，通常與主句的動作同時或緊密相連。它是一個縮減的時間副詞子句。
- when to do 則用於表達「何時該做某事」的「時機」或「決定」，常與 know, decide, ask, tell 等動詞連用，帶有「應該在何時」的含義。
- 簡單區分：when doing 講「在做…的時候」；when to do 講「（知道/決定）何時去做」。
對比例句： EN: I often listen to music when driving. 翻譯: 我常在開車時聽音樂。
EN:I'm not sure when to start the meeting.
翻譯:我不確定該何時開始會議。
EN:Be careful when crossing the street.
翻譯:過馬路時要小心。
EN:Can you tell me when to submit the report?
翻譯:你能告訴我該何時提交報告嗎？
總結建議
描述同時發生的情境用 when doing；表達決定或詢問「該在何時」做某事則用 when to do。
易混淆對比
What is the difference between "When" and similar words?How to choose "When" vs alternatives?
when vs while
when 強調時間點或瞬間動作，while 強調持續時段或同時進行的動作。
when vs as
when 單純表示時間點，as 可表示「隨著」或「一邊...一邊...」。
when vs whenever
when 表示特定時間，whenever 表示「每當」或「任何時候」。
口語用法
How is "When" used in spoken English?What is the spoken vs formal difference for "When"?
引述
在口語中，"when" 常用來引述一個事件或情況，作為對話的開頭或轉折點。 EN: When I heard the news, I was shocked. 翻譯: 我聽到消息時，整個人都愣住了。
EN:That's when everything changed.
翻譯:就是在那個時候，一切都改變了。
語氣強調
在對話中，有時會用 "when" 來強調時間點的重要性或表達驚訝、質疑。 EN: When did you say you were coming? 翻譯: 你剛是說你什麼時候要來？（語氣帶有確認或驚訝）
EN:You're leaving when? Tomorrow?
翻譯:你什麼時候要走？明天？（語氣強調對時間點的意外）
停頓填充
在思考或組織語句時，"when" 有時會被用作口語中的停頓填充詞，類似「嗯」、「那個」的功能。 EN: So, the plan is... when... we meet at the station first. 翻譯: 所以，計畫是…那個…我們先在車站碰面。
EN:I was going to tell her, but... when... I forgot.
翻譯:我本來要告訴她的，但是…嗯…我忘了。
正式寫作注意：在正式書寫或學術文章中，應避免將 "when" 用作停頓填充詞，並確保其引導的從句結構完整、邏輯清晰，以維持文章的嚴謹性。
常見短語
What common collocations use "When"?What fixed phrases with "When" should I remember?
when it comes to
when it comes to [noun/gerund]
當談到...時；在...方面
say when
say when
夠了請說（通常在倒飲料或食物時使用）
hardly/scarcely... when
hardly/scarcely [past perfect] when [past simple]
剛...就...
when in Rome
when in Rome (do as the Romans do)
入鄉隨俗
when all is said and done
when all is said and done
歸根結底；總而言之
when push comes to shove
when push comes to shove
到了緊要關頭；迫不得已時
when the time comes
when the time comes
當時機到來時
when it rains, it pours
when it rains, it pours
禍不單行；不來則已，一來驚人
常見錯誤
What are common mistakes with "When"?Which "When" sentences look correct but are wrong?
×When I will arrive, I will call you.
✓When I arrive, I will call you.
在時間副詞子句中，即使談論未來事件，也不使用未來式（will），而用現在式代替。
×I will go to the park if it is sunny tomorrow.
✓I will go to the park when it is sunny tomorrow.
使用 'if' 表示不確定是否會發生；使用 'when' 表示預期或確定會發生。如果明天天氣晴朗是預期中的事，應使用 'when'。
×When I have eaten dinner, I watched TV.
✓When I had eaten dinner, I watched TV.
描述過去兩個連續動作時，先發生的動作（吃晚餐）應使用過去完成式（had eaten），而非現在完成式。
×When you go to school?
✓When do you go to school?
當 'when' 用於詢問資訊的疑問句時，若主詞是 'you'，必須使用助動詞 'do'（現在式）來形成問句。
×When I was cooking, the phone rang.
✓While I was cooking, the phone rang.
'When' 通常指一個時間點或較短的動作；'while' 強調在一個較長的持續性動作或狀態期間。烹飪是持續性動作，用 'while' 更準確。但 'when' 在此句並非完全錯誤，只是 'while' 更佳。
×When I finish my homework, then I can play games.
✓When I finish my homework, I can play games.
在 'when' 引導的副詞子句中，主句前不需要再加 'then'，因為 'when' 已經表達了時間順序。加上 'then' 雖然可接受，但顯得多餘且不自然。
詞形變化
What are the word forms of "When"?What are tense/participle forms of "When"?