when

1. QUEST You use when to ask questions about the time at which things happen. 什么時候 (用于疑問句，詢問某事發(fā)生的時間)

When are you going home?

你什么時候回家？

When did you get married?

你是什么時候結婚的？

2. CONJ If something happens when something else is happening, the two things are happening at the same time. (表示兩件事同時發(fā)生) 當…的時候

When eating a whole cooked fish, you should never turn it over to get at the flesh on the other side. 吃一整條做熟的魚時，你永遠都不要把魚翻過來吃另一邊的肉。

3. CONJ You use when to introduce a clause in which you mention something that happens at some point during an activity, event, or situation. 當…時 (引導從句，表示從句中提到的事發(fā)生在另一活動、事件或情況期間)

When I met the Gills, I had been gardening for nearly ten years. 我結識吉爾一家時，我已經幾乎做了十年的園藝。

4. CONJ You use when to introduce a clause where you mention the circumstances under which the event in the main clause happened or will happen. 在…情況下 (引導從句，表示從句中提到的情況是主句中已經發(fā)生或即將發(fā)生的事的前提)

When he brought Imelda her drink she gave him a genuine, sweet smile of thanks. 當他給艾梅爾達拿來一杯飲料時，她給了他一個真誠、甜美、表示謝意的微笑。

5. CONJ You use when after certain words, especially verbs and adjectives, to introduce a clause where you mention the time at which something happens. 什么時候 (用在某些詞尤其是動詞和形容詞后，引導從句說明某事發(fā)生的時間)

I asked him when he'd be back to pick me up. 我問他什么時候回來接我。

6. PRON-REL You use when to introduce a clause that specifies or refers to the time at which something happens. 當…的時候 (引導表示某事發(fā)生的具體時間的從句)

He could remember a time when he had worked like that himself. 他還記得當他自己也像那樣工作的那段時間。

7. CONJ You use when to introduce the reason for an opinion, comment, or question. 既然 (用于引入觀點、評論、或問題的原因)

How can I love myself when I look like this?

既然我這么一副樣子，我怎么能愛我自己？

8. CONJ You use when in order to introduce a fact or comment which makes the other part of the sentence rather surprising or unlikely. 而 (引出令人吃驚的事實或評論)

Our mothers sat us down to read and paint, when all we really wanted to do was to make a mess. 我們的媽媽們讓我們坐下讀書、畫畫，而我們真正想要做的卻是胡鬧一陣。