however,but的用法和区别做题的时候应该注意什么?

however前面和后面一般用逗号隔开，单独使用，而but不能后面加逗号，还有语气方面，however语气更轻，but语气更重

1.however作副词用时,表示“然而；但是”,可以位于句首、句中和句末；位于句首时,要用逗号与句子其它部分隔开；位于句中时,其前后都要用逗号；位于句末时其前用逗号分开.例如:
She felt ill.She went to work,however,and tried to concentrate.
她病了.然而她照旧去上班,并且尽力集中精神工作.
His first response was to say no.Later,however,he changed his mind.
他最初的反应是不同意,可是后来他改变了主意.
2.however与but 两者都做“但是,然而”讲,而且都引出并列句.从语义上看,but所表示的是非常明显的对比,转折的意味较however要强.从语序上看,but总是位于所引出的分句之首,而however却可位于句首、句中和句末,同时从标点符号上看,but之后一般不得使用逗号,而however则必须用逗号与句子其它部分分开.例如：
I thought those figures were correct.However,I have recently heard they were not.
我原以为那些数字正确无误,不过我最近听说并不正确.
3.however的其它用法：however可以作连词(conj.),表示“无论以何种方式,不管怎样”,引导让步状语从句.例如：
You can travel however you like.你可以随心所欲地去旅行.
However I approached the problem,I couldn’t find a solution.
这一问题我不管怎样都无法解决.