求翻译：2)在过激流险滩时,上身应稍微前倾,抬高臀部,避免浅滩的岩石撞伤尾椎骨,同时也避免头部撞上山石。是什么意思？

2) in the torrent when the dangerous shoals, upper body slightly forward, raise the buttocks, avoid a shoal of rocks hit coccygeal vertebra, while also avoiding head struck the rocks.