why: [OE] Why goes back to Indo-European *qwei, the locative case of the interrogative base *qwo- (source of English what and who). This passed into prehistoric Germanic as *khwī, which has since died out in all the Germanic languages apart from Danish (hvi) and English (why).
why (adv.)
Old English hwi, instrumental case (indicating for what purpose or by what means) of hw?t (see what), from Proto-Germanic adverb *hwi (cognates: Old Saxon hwi, Old Norse hvi), from PIE *kwi- (source of Greek pei "where"), locative of *kwo- "who" (see who). As an interjection of surprise or emphasis, recorded from 1510s. As a noun, "cause, reason" from c. 1300.
例文
1. You flatter yourself. Why would we go to such ludicrous lengths？
あなたは本当に独りよがりです。私たちはどうしてそんなに力を入れなければならないのですか。
2. Why are Geography，Drama，Art and English in the ascendant？
なぜ地理、演劇、芸術、英語が人気を集めているのか。
3.He wonders why the digits on his calculator slope to the right.
彼はなぜ彼の計算機の上の数字が右に傾いているのか分からない。
4. Why not retrain for a job which will make you happier？
新しいトレーニングを受けずに、より楽しい仕事を探すのはなぜですか。
5. Why should a great community like a university be afraid of nihilism？