Answer -> 一般的な『答え』
They usually don’t answer when they’re busy.
=彼らは忙しい時は電話に出ないです。
That’s a difficult question to answer.
=それは答えづらい質問ですね。
Reply -> 手紙などに対する返事
I don’t know how to reply to that.
=どう返事すればいいか分からない。
I am still awaiting his reply.
=私はまだ彼の返事を待っているのだ。
Response -> 問いかけに対する反応
Expecting a response to this letter.
=ご返信お待ちします。
Thank you for your quick response.
=早急なお返事ありがとうございます。
「テスト」
間違いやすい例
X All of the replies on the test were wrong.
X All of the reponses on the test were wrong.
正しい例
O All of the answers on the test were wrong.
