谁能帮我解答这道英语改错题?I pretended I (thought him mad).But he kept on

I pretended I (thought him mad).But he kept on,(because) I said perhaps he (meant) my brother (who) sometimes came to help me.
(thought him mad):有两种改法 1.thought he is mad
2.thought him madly
(who):应该是whom.这里所要指的是后面的事情.
翻译：我只好假装的认为是他疯了,因为他总是这样；在说他可能是我的弟弟并且有时候还来帮助过我.