"It seems that she was there at the conference." the sentence means that

以现在的眼光看过去的事物-----现在的眼光---seems, 过去的事物---was,的时候,过去的事物就用to加完成时.又如 it seems that she worked here in 2009(主语从句)===== she seems to have worked here in 2009（简单句）.it seems that he was here last wek==== he seems to have been here last week.（ ok了吗?）完成时后面不是不能接过去的时间吗？有这方面的资料和书籍能推荐吗？因为这是非谓语动词的完成时，不是谓语动词的完成时。非谓语动词。我们可以多联系。你几年级？