have seen it all before是什么意思

before have we seen it before and must forgotten it to see what you have seen before it has happened 尤其是 before i have seen it Deceived all i have seen I won't believe you before I have seen it with my own eyes.这 I don't feel like___this film,because i have seen it before What a table!I have never seen such a thing before.It is -- Lay back,it's all been done before这是什么意思? I have never seen _____ film before. I have never seen _____book before. i have seen the film before we have never seen ____art festival before