1.都可表示“除外”，但 besides 表示一种累加关系，意指“除了什么之外，还有……”;而 except 或 but 则表示一种排除关系，意指“除了什么之外，不再有……”。如：

Besides his wife，his daughter also went to see him. 除他妻子外，他女儿也去看过他(即妻子女儿都去看过他)。

Nobody went to see him except [but] his wife. 除他妻子外，没有一个人看过他(即只有他妻子去看过他)。

They all went to sleep except me.除我之外，他们都去睡觉了。

I think she has many good qualities besides being very beautiful.

我觉得她不但长得非常漂亮，而且还有很多优秀品质。

Besides diets, he devised punishing exercise routines.

除了节制饮食，他还设计了魔鬼健身计划。

Besides English, he has to study German and French.

除英语外，他还要学德语和法语。

I had nothing on except for my socks.

我除了短袜什么都没穿。

What other sports do you like besides football?

除足球外你还喜欢哪些运动？

I like all sports except football.

除足球外我喜欢所有的运动。

I like all sports apart from football.

除足球外我喜欢所有的运动。

上述两种含义均可用apart from：

What other sports do you like apart from football?

除足球外你还喜欢哪些运动？

I like all sports apart from football.

除足球外我喜欢所有的运动。

Apart from anything else I was starving.

别的不说，我饿坏了。

Apart from clothes and bedding, I have nothing.

我除了行李被褥之外一无所有。

His one weakness, apart from aeroplanes, is ice cream.

除了对飞机情有独钟，他还嗜好冰激凌。

The room was empty apart from one man seated beside the fire

除了有个男人坐在火炉边，房间里空荡荡的。

There was always something to look forward to, apart from Rachel's visits.

除了雷切尔的来访，总还有别的事情可以期待。

注：在否定句中，besides 也表示“除……之外不再有…… ”，与but, except 同义。如：

No one passed the exam besides [except] Jim. 除吉姆外，没一个人通过考试。

No one writes to me besides you.除你以外，没有人给我写信。

2. 关于 but 与 except：

(1) 两者都可表示“除了”，但含义上略有差别：but侧重指意义的几乎完整性，而 except 则侧重指后面除去的部分。比较：

All are here but one. 除一个人都到了。

All are here except one. 还有一个人没到。

(2) 在现代英语中，but 的介词用法十分有限，一般说来，它只能用在下列词语之后：

① no, no one, nobody, nothing, nowhere 等

② any, anyone, anybody, anything, anywhere 等

③ every, everyone, everybody, everything, everywhere 等

④ all, none 等

⑤ who, what, where 等

Everyone knows it but you. 除你之外大家都知道。

I haven't told anybody but you. 除你之外，我没告诉任何人。

No one but he [him] showed much interest in it. 除他之外没有一个人对此有很大兴趣。

一般说来，若没有出现上述词汇，就不宜使用介词 but，否则可能造成错句。但是 except 却没有以上限制。比较：

正：The window is never opened except in summer. 除夏天外，这扇窗户从不打开。

误：The window is never opened but in summer.

(3) but 一定不能用于句首，except 通常不用于句首：

除我之外每个人都累了。

正：Everyone is tired but (except) me.

正：Everyone but (except) me is tired.

误：But (Except) me, everyone is tired.

注：except for 可用于句首，表示 except 的意思：

正：Except for me, everyone is tired.

3. 关于 except 与 except for：

except 主要用来谈论同类的东西，而 except for 则主要用来谈论不同类的东西，有时含有惋惜之意。如：

All compositions are well written except yours. 除了你的作文外，其他的作文都写得很好。

His composition is good except for a few spelling mistakes. 他的作文写得不错，只是有几处拼写错误。

4. 关于 except for 与 but for：

except for 主要表示排除，but for 主要表示一种虚拟条件(与虚拟语气连用)。如：

Except for me, everyone passed the exam. 除了我之外，大家都通过了考试。

But for my help, she would not have passed the exam. 若不是我的帮助，她就不会通过考试。

But for the atmosphere plants would die. 如果没有大气，植物就会死亡。

注：若用于句首，则 except for 与 except 同义(但 except 通常不用于句首)。

besides 除用作介词外，还用作副词，其意为“此外”、“而且”，可用于分句句首(通常用逗号隔开)或句尾。如：

I don't want to go; besides, I'm too tired. 我不想去，而且我也太累了。

I don't really want to go. Besides, it's too late now.

我并不真的想去。况且现在太晚了。

I don’t think I’ll come on Saturday.I have a lot of work to do. Besides, I don’t really like parties.

我想我星期六不会来。我有好多事要做。再说，我不太喜欢社交聚会。

The task is arduous; besides, there's not much time.

任务艰巨，同时时间又很紧迫。

He doesn't know anything about the matter; besides, he doesn't want to get involved.

他对这件事不清楚，再说，他也不想插手。