?下行易化性网状投射

... 事非经过不知难 not to know how difficult the job is, unless one has done it oneself; a man does not know the difficulty of anything unless he does it personally.; one cannot appreciate the difficulty except through personal experience.; one does not realize the difficulty of an undertaking until one has experienced it oneself 下行易化性网状投射 descending facilitory reticular projection; desending facilitory reticular projection 知难而进,绝不半途而废 press forward without giving up halfway ...