although and but 有何分別?

Although is normally used to indicate an unexpected and negative consequence. For example,

Although he had studied very hard, he failed in the examination. (A student who studies hard should normally pass the examination.)

Although Peter always works hard, his boss does not like him. (A reasonable boss should like to have a hard working subordinates.)

Although Mary is already very beautiful, she is not as beautiful as Elaine.

But is normally used to indicate a choice or preference over others. The choice that is rejected may not be an inferior or negative one. For example,

I enjoy reading but not singing. (Both reading and singing are good hobbies, but you just like reading)

But may also be used to indicate something that you have not attempted before. For example,
I had visited London but not Rome. (You may like both cities, but you have only visited Lonon before.)

Important : Although and but will never use together.

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although and but - 雖然和但
但不可以用於中文法上,
中文文法"雖然"後, 下一句開始用"但"
但英文只用其中一個, 用了although, 就不用But
用了But, 就不用although...

試下用中文的不同詞語看出分別。

although a, b
雖然 a, 不過 b
英文的寫法上 , 之後的「不過」是不用寫的。希望你已經知道although..., but...係錯的寫法 。

although的前後兩樣必須要有相對的關係，b一定要比a優勝或更好。

c, but d
可以是c, 但是也可以是 d; 內容可以相對，但也可以只是另一個選擇或看法。

but的用途多一些，因為前後句未必必須要要有對比的關係，而且可以「但」很多都ok。I like XX, but I like YY and ZZ also。XX YY ZZ之間沒有必然的對立性質，當然YY和ZZ也可以跟XX是相對的東西，所以BUT沒有必然反面的用意。

只可以這樣簡單回答。多看書和文章，自然會留意到前後意思上的各種關係的表達。

although 係「雖然」，but 係「但是」，你可用它們的中文意思決定何時用哪一個。