let out 可以做发泄讲, 而不是let off
let out 可以直接跟宾语,或物主代词加名词
He let out his anger 他发泄他的愤怒
He let out his resentment 他发泄他的愤恨
let out =give vent to 后面都可以跟宾语,+by +v-ing 作方式状语
She let out/ gave vent to her sorrow by breaking the vase 她打碎了花瓶,以发泄她的悲痛。
发泄为let out ,比如对一个需要发泄的人说 It's OK,just let it out,let it out.
let off是放 ,排,宽恕的意思