see sb doing sth 是强调看见某人正在做某事,着重动作过程, 而see sb do sth 是看见某人做某事,着重于看见这件事的发生.如：I saw him drawing by the river then. 我见他那时正在河边画画． I saw him draw by the river sometimes 我看见他有时在河边画画． －－－by an English teacher。