1、 This is the reason why I came so fast. 這就是我來這麼快的原因。
2、I know why he is running fast. 我知道他跑得快的原因。
3、The reason why he did so is unknown. 他為什麼這麼做的原因不清楚。
拓展資料
語源
Middle English
用法
Many critics have held that why is redundant in the expression the reason why, as in The reason why he accepted the nomination is not clear. It is true that why 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
許多批評家認為在the reason why 這種表達中， why 是多餘的， 如在句子The reason why he accepted the nomination is not clear.（他接受提名的原因不太明確。） why 可以從這種例子中除去，對句子意義並不影響， 但是自從文藝復興以來這種結構已為頗有名望的英語作家的廣泛應用參見 where。
why有兩種用法，用Why提問有兩種回答。如下：
Why由兩種用法：
1、構成“Why + 一般疑問句”的特殊疑問句；
2、用從句中，用來解釋理由。
用why 提問通常有兩種回答：
1、Because回答
2、The reason回答
具體用法如下：
一、why可以在句首用作疑問副詞,表示“為什麼”,用來詢問發生某一動作或存在某一情況的原因、理由,構成“Why + 一般疑問句”的特殊疑問句。
例如:
1、Why do you like dogs? 你為什麼喜歡狗?
2、Why are you late for school? 你為什麼上學遲到了？
二、用從句中，用來解釋理由。
例：
1、 This is the reason why I came so fast. 這就是我來這麼快的原因。
2、I know why he is running fast. 我知道他跑得快的原因。
3、The reason why he did so is unknown. 他為什麼這麼做的原因不清楚。
拓展資料語源
Middle English
用法
Many critics have held that why is redundant in the expression the reason why, as in The reason why he accepted the nomination is not clear. It is true that why 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
許多批評家認為在the reason why 這種表達中， why 是多餘的， 如在句子The reason why he accepted the nomination is not clear.（他接受提名的原因不太明確。） why 可以從這種例子中除去，對句子意義並不影響， 但是自從文藝復興以來這種結構已為頗有名望的英語作家的廣泛應用參見 where。