He was not brave enough to report the loss of the documents.
他当时不够勇敢去报失文件的丢失。
If you brave unpleasant or dangerous conditions, you deliberately expose yourself to them, usually in order to achieve something.
勇于置身 (恶劣或危险的环境)
Our men wiped them out, but the enemy fought bravely and well.
我们的人歼灭了敌人,不过敌人也打得很勇猛顽强。