三者均属于表示状态的来连系动词，都有“好像”、“似乎”的意思，区别如下：
(1) seem 侧重指事实上似乎是那样的；look 指视觉印象，指看起来似乎如此；appear 指从表面上看似乎如此，但有时并非如此。。如：
They seemed tired and unhappy when they got home. 他们回到家时看来很累，不高兴。
Be careful! The newly waxed floor looks very slippery. 小心点！这新打蜡的地板看起来很滑。
She appears quite old. 她显得很老。
(2) 三者均可后接不定式，但 look 之后一般只限于 to be(且较少见)：
The man seems / appears / looks to be very tired. 那人好像很疲劳。
He seemed / appeared to have met her before. 他以前似乎见过她。
(3) 三者均可用于 it 开头的句子，且三者之后均可接从句。如：
It seemed / as if / though the day would never end. 似乎白天永远也过不完。
It looked as if he had been ill. 他看起来像是生过病。
It seems / appears that he is very rich. 他似乎很富有。
为避免重复，appear和seem后接的 that 从句有时可用so或 not代替。如：
“Is he an honest man ?” “It seems / appears so / not.”“他是诚实的人吗?”“似乎是 / 不是。”
(4) look, seem 之后可接like短语，但 appear 之后一般不能：
You look like your father. 你看起来像你父亲。
It seemed like a disaster at the time. 在当时就好像是一场灾难。
