英 [wen] 美 [wen]
adv. 什么时候；什么情况下；什么场合下；（用于时间的表达方式之后）在那时，其时；当时，当场
pron. 什么时候；何时
conj. 在……时候；在……之后；在任何……时候；一……就；考虑到，既然；虽然，然而，可是
n. 时间，时候；日期；场合
when /wɛn/ CET4 TEM4
疑问词 You use when to ask questions about the time at which things happen. 什么时候 (用于疑问句，询问某事发生的时间)
When are you going home?
你什么时候回家？
When did you get married?
你是什么时候结婚的？
连词 If something happens when something else is happening, the two things are happening at the same time. (表示两件事同时发生) 当…的时候
When eating a whole cooked fish, you should never turn it over to get at the flesh on the other side.
吃一整条做熟的鱼时，你永远都不要把鱼翻过来吃另一边的肉。
连词 You use when to introduce a clause in which you mention something that happens at some point during an activity, event, or situation. 当…时 (引导从句，表示从句中提到的事发生在另一活动、事件或情况期间)
When I met the Gills, I had been gardening for nearly ten years.
我结识吉尔一家时，我已经几乎做了十年的园艺。
连词 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…情况下 (引导从句，表示从句中提到的情况是主句中已经发生或即将发生的事的前提)
When he brought Imelda her drink she gave him a genuine, sweet smile of thanks.
当他给艾梅尔达拿来一杯饮料时，她给了他一个真诚、甜美、表示谢意的微笑。
连词 You use when after certain words, especially verbs and adjectives, to introduce a clause where you mention the time at which something happens. 什么时候 (用在某些词尤其是动词和形容词后，引导从句说明某事发生的时间)
I asked him when he'd be back to pick me up.
我问他什么时候回来接我。
关系代词 You use when to introduce a clause that specifies or refers to the time at which something happens. 当…的时候 (引导表示某事发生的具体时间的从句)
He could remember a time when he had worked like that himself.
他还记得当他自己也像那样工作的那段时间。
连词 You use when to introduce the reason for an opinion, comment, or question. 既然 (用于引入观点、评论、或问题的原因)
How can I love myself when I look like this?
既然我这么一副样子，我怎么能爱我自己？
连词 You use when in order to introduce a fact or comment which makes the other part of the sentence rather surprising or unlikely. 而 (引出令人吃惊的事实或评论)
Our mothers sat us down to read and paint, when all we really wanted to do was to make a mess.
我们的妈妈们让我们坐下读书、画画，而我们真正想要做的却是胡闹一阵。
"When" - a song by French singer Amanda Lear released in 1980 by Ariola Records.
既然-引用次数：3
参考来源对外汉语成绩测试试题设计研究
时间-引用次数：43
The simulation results show that the identification rate can achieve 99 % and the average identification time is 1.8 ms,when position noise is in the max position error.
仿真实验表明:当位置噪声在估计最大位置误差范围以内时,本算法识别成功率可达99%以上,平均识别时间为1.8 m s,很好地满足了星图识别的要求。
参考来源一种基于星三角形的星图识别算法
什么地方(Where)：从何处取得所需要的材料？在何处做得最好？放置何处最好？往何处送？ 4.什么时候(When)：何时开始最好？何时应当完成？
何时（when）：4月19日中午11点30分 何地（where）：榆林中心城区红山东岳北路旁 何人（who）：有退休在家的干部，有跟随儿女进城的务农老人，...
...常数据会话；行为审计报告：通过对所有操作和访问行为进行追溯，找出可疑人员所在科室，找出可疑人员使用的工具WHEN（什么时间）：细粒度的行为记录与分析，缺乏抗抵赖性。
Until when can you stay?
你可以待到什么时候？
When would they be hired again? Perhaps, as the saying goes, when pigs fly.
他们什么时候会被重新雇用？也许正像俗话说的，等到猴年马月吧。
When will you begin recruiting?
你们何时开始招募人员？
The situation is when farmers have to sell their produce at low prices after harvest, when supplies are greatest.
VOA : special.2009.11.17
And when you have an optimal substructure and the local solutions overlap, that's when you can bring dynamic programming to bear.
当你得到一个最优子结构,但局部解决方案有重跌时，你就可以引入动态编程,来解决这个问题了。
计算机科学及编程导论课程节选 : 麻省理工公开课
when you feel upset or when you feel frustrated that something is not going the way that you wish it would.
当你觉得很失落，或者当你因为事情不像你期望的那样进展而感到沮丧时，你也可以使用这个句型。
SpeakingMax英语口语达人 : I'm frustrated 课堂
It had a long title: "When You Want 'Em,You Can't Get 'Em, When You've Got 'Em,You Don't Want 'Em."
VOA : special.2009.02.08
The leaves make good salads when the plants are young, and the greens can be cooked when the plants are older.
VOA : special.2010.03.02
She told the court when she tried to contact her again, there was no reply.
BBC: Emily Longley trial: Friend calls defendant 'obsessive'
That would at least give the industry certainty about what it must buy and when.
Mr. TAYLOR: That's really a thrill when someone like that picks up your song, you know?