except 和 besides 的区别：
都可解"除……之外"，但含义不同。
except表示"不是所提到的人或事物中的一部分"，做减法运算，含义是否定的。besides表示"除了……之外，还有……"，指是"整体中的一部分"， 做加法运算，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，我们别的人也都去了。(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。
E.g. He had other people to take care of besides me.
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。
e.g. 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。
e.g. She has nothing to do except／besides go with him.
(4)二者后面都可以接
从句。
e.g.
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。
e.g. Your composition is quite excellent except for several spelling mistakes.
②表示非同类事物进行比较。
e.g. The street is empty except for several cars.
③置于句首，表达except的含义。
e.g. 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。
e.g. 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。
e.g. He did nothing besides (＝except) this.
除这件事外，他什么事也没做。
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