You must have read about Dickens long ago,----? A.mustn't yo

1.must have read 表示：一定是做了某事.表达的是已经存在和发生的事情,而且你的句子里还有long ago,很显然是过去的事情.
2.mustn't you是你必须（干某事）吗?意思不对.
3.当have用作助动词时,就可以用Bhaven't you .如they have finished it,haven't they?