YOU SAID:

i slapped my brother so hard

INTO JAPANESE

私は弟をとても強く平手打ちしました

BACK INTO ENGLISH

I slapped my brother very hard

INTO JAPANESE

私は弟を強く平手打ちした

BACK INTO ENGLISH

I slapped my brother hard

INTO JAPANESE

私は弟を強く叩きました

BACK INTO ENGLISH

I hit my brother hard

INTO JAPANESE

私は弟を強く殴りました

BACK INTO ENGLISH

I hit my brother hard