although 和 although 的区别
作为连词的时候，although 和 though 是可以互换的。Although 一般被认为更加正式一些。比如，以下的这些句子：
Growth in Europe is maintaining momentum, although the risks related to peripheral economies have increase. [Globe and Mail]
Unlike the other comparisons, however, this one is apt, though perhaps not in a way Cantor intended. [Washington Post]
Although the birds are just a small part of his business, carefully raising the pheasants from delicate eggs to beautifully feathered birds is clearly a passion. [The Age]
Some grown unschoolers, though positive about it overall, admit they’ve at times longed to be just like the other kids … [National Post]
TheFreeDictionary.com 上面提到，如果用来引领从句（start a clause），那么一般用 although. 这个似乎并不是绝对的规则，即使在引领从句的情况下，although 和 though 似乎依然可以相互替换。
实际上，though 出现的要更早一些，大概在13世纪，although 还没有出现的时候，all though 连用，all 表示强调。
在钦定版圣经的以赛亚书中（Isaiah 1:18 from the King James Bible）：
Though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool.
Although 是一个让步连词（a concessive conjunction），意思是“即使在这中情况下（in spite of the fact that）”
Though 也可以用作副词，意思是 however or nevertheless，这种情形下，although 和 though 是不可以换用的；although 只用作连词
This weekend, though, theaters were packed.[Los Angeles Times]
There was another twist to come, though, as Pavlyuchenkova defied her flagging fortunes to win three games in succession. [Independent]
从上面这些资料来看，如果搞不清楚应该用 although 还是 though，那么 though 是一个不错的选择。
另外，有时候 while 也会有 although 或者 though 的意思。
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