名詞 why:

1. the cause or intention underlying an action or situation, especially in the phrase `the whys and wherefores'
   同義詞：wherefore

1. The reasons why he did it are obscure.
   他做那事的理由還不清楚。
2. Why not let her do as she likes?
   為什么不讓她想怎么做就怎么做呢？

why

adv.（副詞）
For what purpose, reason, or cause; with what intention, justification, or motive:
為什么：為什么目的、原因或起源；以什么目標(biāo)、借口或動機：
例句：
Why is the door shutô Why do birds singô
門為什么關(guān)了ô鳥為什么唱歌ô

conj.（連接詞）
The reason, cause, or purpose for which:
為…的原因、起因或目的：
例句：
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，為什么：
例句：
.The reason why[regular verbs] are called regular is that we can predict what all the other three forms are. (Randolph Quirk)
.[規(guī)則動詞] 之所以稱為規(guī)則是因為我們能夠預(yù)知動詞另三種形式的變化. (倫道夫·夸克)

n.（名詞）
【復(fù)數(shù)】 whys
The 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：
例句：
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.
用于表示輕微的吃驚、生氣或不耐煩

來源：
Middle English
中古英語
from Old English hwt * see k wo-
源自 古英語 hwt *參見 k wo-

Many critics have held thatwhy is redundant in the expression the reason why, as inThe reason why he accepted the nomination is not clear. It is true thatwhy could be eliminated from such examples with no loss to the sense, but the construction has been used by reputable English writers since the Renaissance.See Usage Note at where
許多批評家認(rèn)為在the reason why 這種表達(dá)中， why 是多余的， 如在句子The reason why he accepted the nomination is mot clear.（他接受提名的原因不太明確。） why 可以從這種例子中除去，對句子意義并不影響， 但是自從文藝復(fù)興以來這種結(jié)構(gòu)已為頗有名望的英語作家的廣泛應(yīng)用參見 where