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.
That didn't even make that much sense in English.