YOU SAID:

Crossing the river seemed impossible without an elephant

INTO JAPANESE

象なしは不可能だった川を渡る

BACK INTO ENGLISH

No elephants to cross the River was impossible

INTO JAPANESE

川を渡る象が不可能ではないです。

BACK INTO ENGLISH

Elephant crossing the river has possible is not.

INTO JAPANESE

川を渡る象が可能ではないです。

BACK INTO ENGLISH

Elephant crossing the river has possible is not.