[名师点津]　

　　but作连词还可用于"I'm sorry/Excuse me，but..." 句式中表示歉意，but本身没有意义。

　　I'm sorry，but I can't help you with the problem.

　　很抱歉，我不能帮你解决这个问题。

　　(2)however作副词时，表示"然而，可是，不过"，用以引出令人吃惊或表示对比的话语，可放在句首、句中或句末，但要用逗号隔开。

　　I'd like to go with you，however，my hands are full.

　　我很想和你一块去，可是我太忙了。

　　You may be right.However，I still want to do what I planned.

　　你也许是对的，但我还想按我计划的去做。

　　[名师点津]　

　　however作连词时，表示"无论如何，不管怎样"，相当于no matter how，引导让步状语从句，从句可放在主句之前或之后。常构成：however/no matter how＋adj./adv.＋主语＋谓语。

　　However/No matter how hard you try，it is difficult to lose weight without cutting down the amount you eat.

　　不管你多么努力，如果不减少饭量，减肥很难。

　　He tries his best to solve the problem，however difficult it is.

　　他尽力解决这个问题，不管它有多困难。

　　[即时演练1]　用but/however填空

　　①He is young but very experienced.

　　②However long it takes，I'm going to get the job finished.

　　③Later，however，he changed his mind.

　　2．although 和though的用法

(1)although和though都是引导让步状语从句的从属连词，意为"尽管，虽然"，一般情况下可互换。但although较正式，多用于句首，而though在非正式文体