被动语态中要将省略的to还原的有哪些?麻烦先分一下类,就是什么类型词的要还原to,再举几个常用的例子,

let，make，have，hear，watch，see，feel，notice

hear watch notice see feel listen to（介词，与还原的to不是一回事）这些叫感官动词
let make have（使，让）这些叫使役动词
help（主动语态中可能to本来带着的）

hear listen to watch see notice feel help
he was seen to enter the room.
She was heard to sing in the classroom.