Ⅰ.see sb doing sth. “看见某人正在做某事”，用动词的-ing形式作宾语补足语，表动作正在进行。
Ⅱ.see sb do sth. “见到某人做了某事”，表动作发生了，即动作的全部过程已经结束了。类似的动词还有：hear, feel, watch,等感官动词，及have, let, make等使役动词。如：
① She saw a boy go into your classroom. 她看见一个男孩进了人的教室。
② I saw him walking in the street.我看见他正在街上散步。
③ The teacher heard Jim reading English when she came in. 老师进来时，听见Jim在读英语。