1.相同点

这三个词都可表示“看起来像”、“似乎”，其后均可接形容词、名词、不定式等，且有时可互换。如：

She looks(或seems/appears)(to be)honest.她似乎很诚实。

He looks(或seems/appears)(to be)an honest man.他看起来像个诚实人。

2.不同点

(1)含义上的不同：look着重由视觉而得出的印象;appear强调外表给人的印象，有时含有一种并不符合实际的感觉;seem常指有一定根据的内心判断，这种判断往往与实际情况比较接近。试比较：

He doesn’t look his age.他看起来没有他实际年龄那么大。

He seems very young.他看起来很年轻。

He may appear a fool but actually he’s quite clever.他看起来也许很傻，但实际上他很聪明。

(2)结构上的差别：

1)look和seem之后可接like，而appear之后不能接。如;

He looks(或seems)like a fool.他看上去像个傻瓜。

2)三者之后均可接不定式，但look后接不定式一般只限于to be。如：

She appears to be leaving.或他看上去很累了。

He seemed to laugh初中化学at us.她似乎想走了。

He seemed to laugh at us.他好像在笑我们。

3)三者均可用于以it开头的句子。但要注意：look之后接as if或as though引导的从句，appear之后接that引导的从句，而seem之后可接that也可接as if/as though引导的从句。如：

It looks(或seems)as if you’re right.看来你似乎是对的。

It appears that I am wrong.看来是我错了。

It seems that he is ill.他好像是有病。

注：look在不以it开头的句子里也可后接as if或as though。另外，appear之后有时也可接as if。如：

They looked as if they didn’t care.他们看起来好像不在乎。

It appears as if they’ve lost interest看来他们已失去了兴趣。

4)在there be开头的句子中，可用seem和appear,而不用look。如：

There seems(或appears)to be something the matter with her.他看来像是出了什么事似的。