为什么...？
The full 'why' question embedded in a sentence. Reach for this when you want to ask the reason for something specific — not just a standalone 'Why?' as a follow-up, but a complete question like 'Why is today good?' or 'Why are you happy?' Place 为什么 anywhere that an adverb of reason would fit: at the start of the clause, or right after the subject. It's the workhorse 'why' question; you'll use it dozens of times a day.
Structure
(为什么) [SUBJECT] 为什么 [VERB/ADJ PHRASE]？
wèishénme...?
How to Think About It
为什么 sits where an adverb sits — between the subject and the verb, or sometimes shoved to the front for emphasis. Chinese word order otherwise doesn't change: no inversion like English ('why is he,' 'why did you'). You keep the statement order and just slot 为什么 in. Two valid positions: '你为什么高兴？' or '为什么你高兴？' — both work, with subject-first being more neutral.
Examples
你为什么高兴？
Nǐ wèishénme gāoxìng?
Why are you happy?
他为什么不来？
Tā wèishénme bù lái?
Why isn't he coming?
为什么今年这么忙？
Wèishénme jīnnián zhème máng?
Why is this year so busy?
Common Mistake
Learners invert subject and verb the way English does — '为什么是你高兴？' or '为什么去你？' — because 'why are you happy' inverts. Chinese never inverts for questions; you slot 为什么 into a statement-order sentence and leave everything else alone.
为什么是你高兴？
你为什么高兴？
Don't Confuse With
为什么？ (standalone)
One-word follow-up — 'Why?' Used after someone else has stated a fact. Use the embedded form when the 'why' question is its own complete sentence.
怎么 [VERB]？
'How come...?' — overlaps with 'why' but carries surprise or mild complaint ('怎么这么贵？' = 'How come it's so expensive?'). Use 为什么 for neutral reason-asking; use 怎么 when you're a bit thrown off.
为何...？
Literary/formal synonym of 为什么. Use 为什么 in speech; reserve 为何 for headlines, essays, and rhetorical questions.
Practice
Fill in: 你___高兴？
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为什么
Fill in: ___今年这么忙？
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为什么
Arrange: 不来 / 他 / 为什么 / ？
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他为什么不来？
Translate: Why is he so tired?
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他为什么这么累？
Write a question using 为什么 about something you'd like to ask a friend.
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你为什么想学中文？
Hear It in Real Episodes
This pattern appears in 1 Fluentide episode: