省略 to 的不定式做宾补的动词有：
1、一感feel 形式： feel sb do sth \ feel sb doing sth
2、二听 hear ,listen to 形式：hear sb do sth \ hear sb doing ;
listen to sb do sth \ listen to sb doing sth
3、三让 let,have,make形式：let sb do sth \ make sb do sth
4、五看 see,notice,watch , abserve ,look形式： see sb do sth \ see sb doing sth
这些省略to 的不定式做宾补,在变为被动语态时要还原to
例如：I saw Tom fall off the tree .(变为被动语态)
---Tom was seen to fall off the tree by me .
希望能帮到你
赵老师By the way~主动为listen to sb doing和listen to sb doing sth呢?主动有to的呢？怎么改为被动？含有listen to 变被动的很少，在英语中就出现主动的，英语的语法你就得按照常规的去理解，否则会越学越累。