You're surprised by something, but you don't really know what surprised you; you recognize someone, but you don't really know what cues cause you to recognize that person.
你对某事感到惊讶，但你并不知道是什么让你感到惊讶;你认出了某人，但你并不知道是什么线索让你认出了那个人。
标签
Surprised