一、作为连词（Conjunction）：表示转折
1. 连接两个相反/对比的概念
结构：句子1 + but + 句子2
例：
She is young, but she handles pressure well.
I tried to call him, but his phone was off.
注意：
句中通常用逗号分隔前后分句。
口语中可省略逗号：I like coffee but I prefer tea.
2. 固定句型：Not…but…（不是…而是…）
结构：否定部分 + but + 肯定部分
例：
Success is not about luck, but hard work.
He’s not a teacher but a doctor.
注意：前后成分需对等（名词对名词，动词对动词等）。
二、作为介词（Preposition）：表示“除了”
1. 与否定词（no, nobody, nothing）或疑问词（who, what）连用
例：
Nobody but you can solve this problem.
What is it but a mistake
2. 常见搭配
anything but（绝不）：This is anything but easy.
all but（几乎）：The project is all but finished.
注意：介词用法中，but 后接名词/代词宾格：
正确：Everyone left but me.（非“but I”）
错误： Everyone left but I.
三、独特用法与固定表达
1. Cannot help but do sth.（不得不做）
例：I can’t help but laugh at his jokes.
2. But for（若非…）
例：But for your help, I would have failed.
3. But that（引导条件状语从句）
例：He would have come, but that he was ill.
四、常见错误与注意事项
1. 避免与 although/since 连用：
错误： Although it rained, but we went out.
正确：It rained, but we went out.
2. 句首慎用 but：
正式写作中避免： But I disagree.
口语/非正式写作可用：But why did you do that
3. 区分 but vs. however：
but 直接连接分句，however 可独立使用：
He is poor, but he is happy.
He is poor. However, he is happy.
五、聊到这里表
| 用法 | 结构/搭配 | 例句 |
| 连词（转折） | 句子1, but 句子2 | I tried, but it didn’t work. |
| 固定句型 | not…but… | It’s not cheap but effective. |
| 介词（除了） | nobody/anything + but… | All but one student passed. |
| 独特表达 | cannot help but… | She can’t help but smile. |
希望这份拓展资料能帮助你精准掌握 but 的用法！
