这个句子的确是错了.首先我说下see sb do的结构中的do并非谓语动词而是省略to的不定式,像 see find hear observe等感官动词和make这个使役动词后都可接不带to的复合宾语
不违背谓语动词单一原则.看下两句你就明白了
I see him eat this cake.= I see that he eats this cake.
He is seen to eat this cake.(see变被动时 to要加上）