see, hear, look,notice,watch,后接不带to 的动词不定式做宾补(用法同使役动词let,make,have),也可接现在分词做宾补.如：
I heard him singing/sing in the next room just now.我刚才听见他在隔壁唱歌.
接不定式表示动作全过程,接现在分词强调正在进行.
在被动语态中,要把to补上.如He was heard to sing in the next room just now.
顺便说一下,feel,taste,smell,seem.look等虽然表示感觉,但常用作系动词,后接形容词作表语.
