There is nothing to do but to pray for the best and plan for the worst and go on from there.

英訳に間違いが有れば正してください。

最善を祈り、最悪の事態に備えてそこから先へ進む以外に何もすることはありません。
There is nothing to do but to pray for the best and plan for the worst and go on from there.

答え
to prayをprayにする

There is nothing to do but pray for the best and plan for the worst and go on from there.

There is nothing to do but原型動詞
それ以外することがないの意味