（1）二者都可以作“看起来”讲，但seem暗示凭借一些迹象作出的有根据的判断，这种判断往往接近事实；look着重强调由视觉得出的印象。两者都可跟（to be）+形容词和as if从句。如：He seems / looks （to be） very happy today. 他今天看起来很高兴。
It looks （seems） as if it it is going to rain. 好像要下雨了。
（2）但下列情况中只用seem不用look：
①后跟不定式to do时。如：He seems to know the answer. 他似乎知道答案。
②在It seems that …结构中。如：It seems that he is happier now than yesterday.他像比昨天高兴些了。