Learner's definition of WHY
1
: for what reason or purpose为什么；为何 -
Why did you quit your job?你为什么辞职了？
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Why are you laughing? [=what are you laughing about?]你笑什么？
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Why is the sky blue?天空为什么是蓝色的？
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Why didn't you call me?你为什么没给我打电话？
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Why didn't I think of that?我怎么没想到那一点？
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“I can't go out tonight.” “Why not?”“我今晚不能出去。”“为什么不行？”
2
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used to offer a suggestion or to say that a course of action is not necessary为什么（用于提出建议或说明某些行为没有必要） -
If you don't want to go, why not just say so?如果你不想去，为什么不直接说呢？
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Instead of calling, why not e-mail instead?别打电话，干吗不发电子邮件呢？
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Why should I care about that?我为什么要在乎那件事？
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Why don't you come over for dinner? [=we would like to have you over for dinner]你过来跟我们一起吃晚饭吧？
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You deserve the best treatment. Why settle for less? [=you shouldn't be happy with anything less]你应该受到最好的待遇，干吗要将就呢？
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“I'll try calling again.” “Why bother?” [=it's not worth the trouble]“我会再试着打电话的。”“何必麻烦呢？”
3
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used to express irritation or annoyance为什么（表生气或恼火） -
Why can't you make up your mind?你为什么就不能下定决心呢？
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Why must I always repeat myself?为什么总要我重复说过的话？
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Why would anyone say such a thing?为什么会有人说出这样的话？
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Why oh why did I say something so stupid?我怎么会说这种蠢话呢？
2 why /ˈwaɪ/ conjunction
Learner's definition of WHY
1
: the cause, reason, or purpose for which为什么 -
I know why he did it.我知道他为什么这么做。
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It's easy to see why she fell in love with him.为什么她会爱上他，这很容易明白。
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He's a very good player. That's why he made the team.他是名优秀选手，这就是他加人这支队的原因。
3 why /ˈwaɪ/ noun
Learner's definition of WHY
the whys and (the) wherefores
: the reasons for something理由；原因 4 why /ˈwaɪ/ interjection
4 why
/ˈwaɪ/
interjection
Learner's definition of WHY
somewhat old-fashioned
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used at the beginning of a statement especially to express surprise哎哟（用于句首，尤表吃惊） -
Why, I can't imagine such a thing!哎哟，想不到会有这种事！
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“Do you know him?” “Why, yes! We know him quite well.”“你们认识他吗？”“噢，当然！我们跟他很熟。”
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“Would you like another drink?” “Why, yes. Thank you.”“你想再来杯饮料吗？”“嗯，好的。谢谢。”
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If I want a drink, why, I'll just get it myself!如果我想喝，嗬，我会自己去拿！
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Why, of course! That makes perfect sense.啊呀，当然！这样合情合理。