YOU SAID:

when the cow went to the party, he slept.

INTO JAPANESE

牛がパーティーに行ったとき、彼は眠りました。

BACK INTO ENGLISH

He slept when the cow went to the party.

INTO JAPANESE

牛がパーティーに行ったとき、彼は眠りました。

BACK INTO ENGLISH

He slept when the cow went to the party.