从方框中选出所缺的短语。并用其适当形式填空

believe in，ahead of，set out，deal with，make mistakes

We don’t know how to________the problem．We need help．
They went to the port and________early．They are going to sail across the river．
She________in the exam，so she failed in the exam again．
Do you really________the existence of God？
I think the work can be completed________time．