but 是連詞,連接兩個并列句,中間用逗號隔開.表示轉(zhuǎn)折
如：I wanted to buy a book,but I don't have enough money.
though 是副詞,但在句中的成分相當于連詞.引導從句,不能與but 連用,可以放句首或者句中.意思是盡管,though 和although不可以與but連用,
1.(al)though 是從屬連詞連接一個從句,but是并列連詞連接一個并列句,一個句子要么是主從句要么是并列句,所以兩者不可能出現(xiàn)在同一個句子中,只能單個使用：
Although it was expensive,we decided to buy the computer.=The computer was expensive,but we decided to buy it.
2.however語氣比but強,但由于同樣的理由不能與(al)though 出現(xiàn)在同一個句子中.
如：Though it is so hot I have to go outside.
I have to go outside though it is so hot.
however 也是副詞,劇中成分相當于連詞.可以放在句首或句中,后面一定要用逗號.表轉(zhuǎn)折.放句首時,與前面的句子是轉(zhuǎn)折的連接.放句首時,前后用逗號隔開
如：I wanted to buy a book,however,i do not have enough money.
區(qū)別：①although和though同義,在一般情況下,可以互換使用.只是though較普遍,常用于非正式的口語或書面語中,而although則較為正式.另外although語氣比though重,常用以強調(diào)讓步概念.
e.g.Though/Although my car is very old,I don't want to buy a new one.
雖然我的汽車很舊,但我不想買一輛新的.
He insisted on doing it although I warned him not to.
雖然我警告他不要做,但他仍然堅持要做.
②even能和though組合表示強調(diào),但even不能和although組合.因此,不能說even although,在這里even though=even if(no matter if; though即使……也……)
e.g.Even if/Even though we could afford it,we wouldn't go abroad for our vocation.
即使我們付得起這筆錢,也不出國度假.
③當讓步狀語從句指某種假設情況時,通常用though,而不用although.
e.g.Though all the world were against me,I should still hold to my opinion.
就算全世界都反對我,我還是堅持我的立場.
Though everybody deserts you,I will not.
即使所有人都拋棄你,我也不會的.
④though可以獨立用作副詞,常放在句末,意為all the same (還是；仍然)或however(可是；然而),而although無此用法.
e.g.She didn't tell me what she had done,but I know it though.
她沒有告訴我她所做的事情,但我還是知道了.
It's hard work.I enjoy it,though.
工作很苦,可是我喜歡.
⑤though引導讓步狀語從句時可以倒裝,而although從句則不能.
e.g.Bravely though they fought,they had no chance of winning.
雖然他們打得很勇敢,但還是沒有機會獲勝.
相同點：①在although和though引導的讓步狀語從句中,主句里不可用but,若要強調(diào)前后兩部分的對比意義,可在主句前加yet或still.
e.g.Although/Though he has a lot of money,yet/still he is unhappy.
他雖然有很多錢,但并不幸福.
②although和though引導讓步狀語從句時,常采用省略形式.
e.g.Although tired (=Although he was tired),he kept on working.
雖然很疲勞,但他繼續(xù)工作.
The problem,though complicated(=though it is complicated),can be solved without much difficulty.