used to introduce an added statement, usually something that is different from what you have said before

She's very hard-working but not very imaginative. 她工作很努力，但缺乏想象力。

This is not caused by evil, but by simple ignorance. 这并不是恶意而为，只是由于无知。

The play's good, but not that good - I've seen better. 这出戏还可以，但也不是多好——我看过更好的。

I'm sorry, but I think you're wrong when you say she did it deliberately. 对不起，我觉得你不能说她是故意那么做的。

Call me old-fashioned, but I like handwritten letters. 叫我老古董好了，反正我喜欢手写的信。

I can understand his unhappiness. But to attempt suicide! 我可以理解他很不快乐，但自杀有点太极端了吧！

"She said she's leaving." "But why?" “她说她要走。”“可是为什么呢?”

You can invite Keith to the party, but please don't ask that friend of his. 你可以邀请基思参加聚会，但请不要邀请他的那个朋友。

We must not complain about the problem, but (= instead we must) help to put it right. 我们不应该抱怨问题，而是应该帮助解决问题。

She's not a painter but a writer (= she is a writer, not a painter). 她不是画家而是作家。

She's not only a painter but also a writer (= she is both). 她不仅是画家而且是作家。

UK He said he hadn't been there, but then (= it is not surprising that) he would say that. 他说他没去过那儿，不过他那么说也不奇怪。

UK I think it's true, but then (= it should be understood that), I'm no expert. 我认为这不假，不过我并非专家。

except

Eventually, all but one of them promised to come to his birthday party. 最后，除了一个人外，他们都答应来参加他的生日聚会。

He's anything but violent (= not violent in any way). 他一点也不粗暴。

I would have crashed the car but for your warning. 要不是有你的警告，我早就把汽车撞坏了。

This is the last episode but one (= one before the last) of the series. 这是这部系列剧的倒数第二集。

She's one of those guests who does nothing but complain. 她是那种只知道抱怨的客人。

This car has been nothing but trouble - it's always breaking down! 这辆汽车哪儿都有毛病——老是坏！

used to give force to a statement

Everyone, but everyone, will be there. 每个人，请注意是每个人，都必须到。

only; just

She's but a young girl! 她只是个小女孩！

used to emphasize that something will happen even if the person you are talking to does not want it to

We're going to visit your aunt tomorrow and there'll be no buts about it. 我们明天要去看望你的婶婶，一定要去，没有商量的余地。

"I know I said I'd start that essay tonight but I'm tired." "No buts about it - you're making a start tonight."

I want that bedroom cleaned today and there'll be no buts about it.

"I'm not sure I want to go to the gym." "No buts - we're going!"

We're leaving now. No buts, come on!