But 作为连词在大多数情况下都用作并列连词，但有时在一些固定结构中也可用作从属连词。 一、用作并列连词 作为并列连词，but 可以连接两个并列的分句或者两个并列的成份，译为“但是”，“可是”。能表示下列意义：
1、表示意义转折。例如：
They are tired but happy.
I was going to write, but I lost your address.
Not one but two!
2、表示对比或对照，通常与否定词连用。例如：
He is not good at maths, but he is good at English.
He scarcely knows French, but he speaks English perfectly.
3、出现在句首或句与句之间，表示异议，惊奇或吃惊。如：
A:I have won the long jump.
B:But that‘s wonderful!
4、用在表示歉意的词语之后，引起一个句子，长不能译为“但是”，可以不译出。如：
I‘m sorry, but I can‘t come.
Excuse me, but can you tell me the way to the library?
固定短语：1、not only … but (also) … 这是一组关联并列连词，表示其所连接的成份在意义上后一项对前一项的补充和引申，法语论文，但侧重点在后一项上，意思是“不但……而且……”。但使用这一组关联并列连词必须注意两点：
(1)、当 not only … but also 连接两个并列成份作主语时，其谓语动词的形式按照就近准则来确定。
(2)、当 not only … but also 连接两个并列成份时采用部分倒装形式，即倒装 not only 分句，而 but also 分句则采用陈述句语序。如：
△ Not only the mother but also the children are sick.
△ Not only is he interested in the subject but also all his students are beginning to show interested in it.
有时，but 和 also 可以被分隔使用。如：
She was not only compelled to stay at home but she also forbidden to see her friends.
有时，but also 能被 but … as well 所取代。如
He can not only speak English but French as well.
2、but then, 意思是“不过，另一方”，相当于 nevertheless, on the other hand”。如：She speaks English fluently, but then she did live in London for four years.3、not that … but that … 引导两个并的原因状语从句，that 相当于 because, 意思是“不是因为 …… 而是因为 ……”。如：
I haven‘t worked out the maths problem, not that I have no time for it, but that I can‘t work it out. 有时 not that … but that … 结构可单独出现。如：
Not that I won‘t go, but that I don‘t know which is the way to go.
二、用作从属连词。
But 在一些固定结构中作从属连词，引导状语从句和名词从句。
1、引导条件状语从句。
But that 可以用来引导条件状语从句，意思是“倘若，法语论文题目，要不是”。牛津现代高级法汉双解词典和一些语法书上将此结构中的 but 看成介词，that 则引导了特殊的介词宾语从句，但是牛津现代高级法汉双解词典和章振帮先生所着新编法语语法等认为 but that 为复杂从属连词， but that 从句为条件状语从句，本人倾向于后一种看法。 That 从句一般不作介词补足成分，将 but that 理解为复杂从属连词，有助于确切理解从句 but that 的真正意义， but that 从句用陈述语气，而主句则常用虚拟语气，but that 从句可以同否定的 if 从句互换。
1 | 
