I must have done something right.这一句应该怎么翻译?

问题描述:

I must have done something right.这一句应该怎么翻译?
是说:我过去肯定做了某件对的事情?还是说:我过去做的肯定对?
能引申出一个被动语态:
Something must have been done someone right.吗?

我过去肯定做了某件对的事情
Something must have been done someone 这肯定不对应该在someone前面加一个by,表示事情是被某一个人做的,这才是被动呀.