YOU SAID:

may I buy you a coffee?

INTO JAPANESE

コーヒーを買ったことがありますか。

BACK INTO ENGLISH

Have you bought a cup of coffee.

INTO JAPANESE

一杯のコーヒーを購入しています。

BACK INTO ENGLISH

Buy a cup of coffee.

INTO JAPANESE

一杯のコーヒーを購入します。

BACK INTO ENGLISH

Buy a cup of coffee.