问一个表语从句it seems you keep getting flashback from your previou

是省略了that,it seems （that） 是固定句型,“似乎”,我想因为it是单数所以才为seems而不是seem吧.无可厚非seems后面的是表语了,keep后一般接形容词的,其后动词形式常为doing,也可加上个from构成短语.重申下该句为宾语从句非上楼说的主语从句,话说若真是主语从句,那主系表结构的表语呢?难不成还主谓?