手早い答え
4つのつづりは、質問・理由の説明・文末の質問・名詞という4つの役割を持ちます。
確実な見分け方は、英語から訳す前に、その単語の働きを見きわめることです。
それぞれの単語の働き
por que
why or for which
Use por que for a direct or indirect question, or por plus the relative que.
porque
because
Use porque for an answer, explanation, or cause.
por quê
why at the end
Use por quê for a question form placed at the end of a clause.
porquê
the reason
Use porquê for a noun, normally after an article or other determiner.
選び方
- por que: Choose por que if the sentence points to a direct or indirect question, or por plus the relative que.
- porque: Choose porque if the sentence points to an answer, explanation, or cause.
- por quê: Choose por quê if the sentence points to a question form placed at the end of a clause.
- porquê: Choose porquê if the sentence points to a noun, normally after an article or other determiner.
例文
Por que você saiu cedo?
Why did you leave early?
Saí cedo porque estava cansado.
I left early because I was tired.
Você saiu cedo por quê?
Why did you leave early?
Ninguém explicou o porquê.
Nobody explained the reason.
よくある落とし穴
Do not choose by sound; they sound alike. Check whether the expression asks, explains, ends the clause, or names a reason.
文脈の中で練習する
自分の実生活から文を一つ選び、二回書いてみましょう。一度はpor queで、もう一度はporqueで。どちらも成り立ちそうなら、意味の違いを言葉にしてみましょう。