系动词之 感官动词知识点讲解1. 感官动词用法之一:see, hear, listen to, watch, notice等词,(后接宾语,再接动词原形或ing形式。前者表全过程,后者表正在进行。句中有频率词时,以上的词也常跟动词原形。) I heard someone knocking at the door when I fell asleep. (我入睡时有人正敲门) I heard someone knock at the door three times. (听的是全过程) I often watch my classmates play volleyball after school. (此处有频率词often) 若以上词用于被动语态,后面原有动词原形改为带to不定式: We saw him go into the restaurant. He was seen to go into the r