YOU SAID:

you can't stop an avalanche as it races down the hill

INTO JAPANESE

雪崩は丘を駆け下りるので止めることはできません

BACK INTO ENGLISH

The avalanche runs down the hill so it cannot be stopped

INTO JAPANESE

雪崩は丘を下って走るので止めることはできません

BACK INTO ENGLISH

The avalanche runs down the hill so it cannot be stopped