AHD:D.J.K.K.adv.（副詞）For what purpose, reason, or cause; with what intention, justification, or motive:Why is the door shut? Why do birds sing?門為什麼關了?鳥為什麼唱歌?conj.（連線詞）The reason, cause, or purpose for which:為…的原因、起因或目的：I know why you left.我知道你離開的原因Usage Problem On account of which; for which:【用法疑難】 因為，為什麼：“The reason why are called regular is that we can predict what all the other three forms are” (Randolph Quirk)“ 之所以稱為規則是因為我們能夠預知動詞另三種形式的變化” (倫道夫·夸克)n.（名詞）【複數】 whysThe cause or intention underlying a given action or situation:原因，動機：在一特點行為或情況下隱藏的起因或目的：studying the whys of antisocial behavior.研究反社會行為的原因A difficult problem or question.難題，令人費解的問題interj.（感嘆詞）Used to express mild surprise, indignation, or impatience.用於表示輕微的吃驚、生氣或不耐煩
Middle English中古英語from Old English hwthorn;} * see k wo-源自 古英語 hwthorn;} *參見 k wo-