為何的用法和樣例：
例句
-
羅馬帝國為何衰亡？
What made the Roman Empire decay? -
你一定要急急忙忙走嗎？為何不留下喝杯茶呢？
Must you dash off? Why not stay for a cup of tea? -
我要發火了，你為何瞞我這麼多事？
I shall lose my temper. Why do you hide so much from me? -
我不知道他為何辭去他的職務。
I have no idea why he resigned his post. -
那就是他為何哭的原因。
That's (the reason) why he cried.
