YOU SAID:
I killed thirteen men on the train yesterday.
INTO JAPANESE
私は昨日電車の中で13人の男性を殺した。
BACK INTO ENGLISH
I killed 13 men on the train yesterday.
INTO JAPANESE
私は昨日電車の中で13人の男性を殺しました。
BACK INTO ENGLISH
I killed 13 men on the train yesterday.
You've done this before, haven't you.