我认为 楼主是 让 修改 英语 句子的
应该是 He doesn't seem to have konwn that his grandfather has left a lot of money for him.
他看起来不知道他的祖父给他留了一大笔钱.
也可以 这样表达 it seems that he doesn't konw( that) his grandfather has left a lot of money for him