YOU SAID:

if a cow cows a cow, the cow will be milked

INTO JAPANESE

牛が牛を搾乳する場合、牛は搾乳されます

BACK INTO ENGLISH

When a cow milks a cow, the cow is milked

INTO JAPANESE

牛が牛を搾乳するとき、牛は搾乳されます

BACK INTO ENGLISH

When a cow milks a cow, the cow is milked