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used to introduce a word or phrase that contrasts with what was said before 而；相反 -
however; despite this 然而；尽管如此 I'd asked everybody but only two people came. 每个人我都请了，却只来了两个人。 By the end of the day we were tired but happy. 一天结束时，我们很累，但很高兴。
Language Bank neverthelessneverthelessConceding a point and making a counterargument 承认一个观点的正确性，并提出一个对立的观点 While the film is undoubtedly too long, it is nevertheless an intriguing piece of cinema. 虽然这部电影的确太长了，但它不失为一部有趣的影片。
It can be argued that the movie is too long. It is nonetheless an intriguing piece of cinema. 可以认为这部电影太长了，但它不失为一部有趣的影片。
The film is undoubtedly too long. Still, it is an intriguing piece of cinema. 这部电影的确太长了，但它仍不失为一部有趣的影片。
Of course, huge chunks of the book have been sacrificed in order to make a two-hour movie, but it is nevertheless a successful piece of storytelling. 当然，为了制作一部两小时的电影，该书中的大部分内容都被舍弃了，不过它仍不失为一部成功的故事片。
Critics are wrong to argue that the film’s plot is too complicated. Certainly there are a couple of major twists, but audiences will have no difficulty following them. 批评家认为这部电影的情节过于复杂，这种观点是不恰当的。影片中确实有几次大的情节变化，但观众还是不难看懂的。
It is true that you cannot make a good movie without a good script, but it is equally true that a talented director can make a good script into an excellent film. 的确，没有好的剧本不可能拍出好的电影，但有天赋的导演能将较好的剧本制作成非常好的电影，这一点也是没有疑问的。
It remains to be seen whether these two movies herald a new era of westerns, but there is no doubt that they represent welcome additions to the genre. 这两部电影是否预示着西部片新时代的来临还有待观察。但是毫无疑问，它们作为这一电影类型的新作而受到欢迎。
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used when you are saying sorry about something （表示歉意时说） -
used to introduce a statement that shows that you are surprised or annoyed, or that you disagree （引出下文，表示吃惊、生气或不同意） But that's not possible! 但那是不可能的！ ‘Here's the money I owe you.’ ‘But that's not right—it was only £10.’ “这是我欠你的钱。” “但这不对呀，我只借了 10 英镑给你。”
except 除…外；只有 used before repeating a word in order to emphasize it （重复字词前用，加强语气） - (literary)
used to emphasize that something is always true （强调一贯真实） She never passed her old home but she thought of the happy years she had spent there (= she always thought of them). 她每次经过自己的旧居，都会想起在那里度过的幸福岁月。
Word OriginOld English be-ūtan, būtan, būta ‘outside, without, except’ (see by, out).
Idioms
but for
but then (again)
however; on the other hand 然而；另一方面 used before a statement that explains or gives a reason for what has just been said （引出解释或原因）
you cannot/could not but…