1.except和besides都可解作“除……之外” 但含义不同.
except 表示“从所提到的人或事物中除去,即从整体中除去一部分”,表示递减的概念,含义是否定的.
besides表示“除了……之外,还有……”,指“在整体中加入一部分”,表示递加的概念,含义是肯定的.
试比较：
①We all went except him.除他之外,我们都去了.(他没有去)
②We all went besides him.除他之外,我们大家也都去了.(他也去了)
(1)besides常与other／more／else等词连用 ,except常与all／every／everyone／none／nobody／everything／nothing等总括词连用.
eg.He had other people to take care of besidesme.
All the students in Class One went to the cinema except Li Ping.
(2)若句中没有实义动词do的某种形式,except后接动词不定式,而besides后接动词的-ing形式.
eg.I had no choice except to obey／besides obeying his order.
(3)若句中有实义动词do的某种形式,二者后面都可以接动词原形.
eg.She has nothing to do except／besides go with him.
(4)二者后面都可以接从句.
eg.①Besides that he explained the theory he gave us some examples.
②He is a good student except that he sometimes comes late to school.
(5)except后面可接for(构成短语except for)或其他介词短语,而besides不能.
except for主要有三层含义：
①表示对整体主要部分的肯定和对局部的否定,起部分修正主要意思的作用.
eg.Your composition is quite excellent except for several spelling mistakes.
②表示非同类事物进行比较.
eg.The street is empty except for several cars.
③置于句首,表达except的含义.
eg.Except for this,everything is in order.
except for后接名(代)词,可以转移为except＋从句或其他介词短语.
eg.The climate here is good except for some rainy days.(except when it rains；except that it sometimes rains；except on the rainy days)
注意：二者用于否定句时含义相同,意思是一样的.
eg.He did nothing besides (＝except) this.
除这件事外,他什么事也没做.
2.apart from兼有besides和except for两种含义,后接名词、代词或动名词.
3.but含义与except相同,都表示递减的概念,二者在多数情况下可以互换,但用法稍有区别.
①except可以代替but,但but并不一定都可以代替except,如果句中有no、all、nobody、who、where等不定代词或疑问词时,多用but；后跟宾语从句时,多用except.
②but for含义有时与except for相同,但主要表示“要不是……”,常用于虚拟句,表示一种假设.
③but位置的变化会引起人称代词主、宾格的变化.