I believed by the end of that year an advanced version of that software would have been developed,but I was wrong .
译：到那年年末我相信那个新的软件的先进版本已经被发明,但是我错了.
析：因为would have been developed在此句中是表被动,因此不能去掉“been”.
过去将来完成时
should / would have done sth.
用法
1、 过去将来完成时表示在过去将来某一时间以前发生的动作,并往往会对过去将来某一时间产生影响.
2、 过去将来完成时还常用在虚拟语气中,表示与过去的事实相反.