1.except 后接名词、代词、不定式、介词短语
2.except 后一般可跟名词性从句,except此时为连词,except for为介词短语,不接从句.换句话说,即介、连词前只能用except
I like her except when she is crying.
I can't spare any time except on Saturday.
3.在以except连接的句子中,可将except的某些词与其后的词重新组成一个语义完整、逻辑通顺的句子
He desired nothing except to see Chairman Mao.
He desired to see Chairman Mao.
The room was virtually empty except for a bench or two.
The room was a bench or two (不成立).
4.except for含有大体上可以,但有部分不够好,“美中不足”,有令人“惋惜”之意
Achilles was invulnerable except for his heels.阿基里斯除脚踵外,全身刀枪不入.
5.except for之前说明句子的基本情况,而其后部分则引述了相反的原因或细节,“非同类比较”,意为“要不是”,“只是”
The carpet is good except for its price.地毯很好,只是价钱太高.
6.在一些含有except for的句子中,如可以把except for之前的某些词与其后的某些词组成一个独立的句子,则except for与except可以互换使用,但在书面语中常常用except
Everybody had a wonderful time except for John.(except for =except)
重新组合句子为：John had a wonderful time.
7.在all,any,every,no,anything,anybody,anywhere,whole这些表示总体概念的词后面,可用两者：except或except for,其他情况用except for
We are all here except / except for John.
8.句首不能用except,而用except for
Except for John,we've all here.
9.except前后的词(名、代)是平行的,应是同性质的词,否则用except for
The students exercises are good except John's.
Your exercise is good except for a few spelling mistakes.
10.besides与but意义不同,但用在no或not等否定词后面,意思相同
We have no other tools besides / but these.除这些以外,我们没有别的工具.
11.except较but除外的意思更明确,排除性更强,except所述的事物不在总体范围之内
I've written all my letters but one.
We all went except Mary.
12.在否定句中except与besides可互换使用,except for则不能
No one writes to me except / besides you.
