I've really got nothing to complain of最后又of,即complain of

I've really got nothing to complain of最后又of,即complain of I have nothing to complain of.为什么要加of? I have nothing to complain of really.这句话的结构我觉得怪怪的 complain of ,complain to,complain about的意思及区别 complain to,complain about,complain of 三者有何区别? We have nothing to complain.还是We have nothing to complain of complain of sth.to sb. 用介词填空1.as----me,I have nothing to complain of 2.the poor man complain of sb. acknowledgement of complain complain of等于complain about吗? 用 complain to sb of sth 造句