have sb do sth 让某人做某事（do前的to省略,或者说不能加）
have sb doing sth 其实也有,但一般用keep sb doing ,让某人一直做某事
have sth to do 有某事要做 如,i have a lot of homework to do也就是说没有have sb to do了？不是绝对没有，假如说“我有某个人要处理”也行的啊，hve sb to deal with （只不过是把have sth to do 变化了宾语，当然这个用法不常见）