选B
Where did you go the day before yesterday?--I( have been in )Shanghai for two days.
你前天去哪里了?--我去了上海2天.
明显是过去完成时.(过去在上海,现在不在了)
而have been是现在完成时.
过去完成时和现在完成时的区别:
过去完成时动作发生在过去的过去.试比较以下现在完成时和过去完成时的两个句子
如:He has been to Beijing twice.他已经去过北京两次 （现在完成时）
He said he had been to Beijing twice.他说他已经去过北京两次.（因为“说”said就是过去式,而去北京的动作发生在说said 的过去,所以用过完而不用现完.
过去完成时常用的时间状语有 1.by the end of last year.
By the end of last term,we had learned 5000 new words.
2.By the time sb.+动词过去式 如：The bus had already left by the time I got there.
3.宾语从句