他的第一反应是不同意，可是他后来改变了主意。

　　He hasn't arrived. He may, however, come later.

　　他还未到，不过，他可能晚一会儿来。

　　[名师点津]　however还可以用作从属连词，意为"无论如何，不管怎样"，引导让步状语从句。

　　You should always try to achieve more, however well you have done before.

　　不管以前做得多么好，你始终应该争取更大的进步。

　　2．but

　　but是并列连词，意为"但是"，常用来连接两个并列的句子或一个句子中的两个并列成分，表示对比、转折。

　　I'd asked everybody but only two people came.

　　 每个人我都请了，却只来了两个人。

　　Tom went to the party, but his brother didn't.

　　 汤姆去参加聚会了， 他的兄弟却没去。

　　3．while

　　while用作并列连词时，意为"却，然而"，表示对比或用于引出相反的情况。

　　White­collar (白领) workers in China are willing to postpone their retirement age while blue­collar workers prefer to retire early.

　　 中国白领个人更愿意推迟他们的退休年龄；而蓝领工人更愿意早退休。

　　集中演练1

　　1－1.用however, but或while填空

　　①We had invited him, but he didn't come to the party.

　　②He said that it was so; he was mistaken, however．

　　③You like sports, while I'd rather read.

　　④Sailing in rough weather could be very unpleasant. However, we found it exciting.

　　⑤He tried hard but did not succeed.

　　1－2. 用括号中的词连接两个句子

　　⑥Tom planned to move to Beijing. He decided not to leave here. (however)

　　→Tom planned to move to Beijing. However, he decided not to leave here.

　　⑦It is hot in summer here. It is not cold in winter. (while)

　　→It is hot in summer here while it is not cold in winter.

　　⑧She likes bread and milk a little. She doesn't like eggs at all. (but)

　　→She likes bread and milk a little but she doesn't like eggs at all.

⑨You like playing tennis. I like reading. (while)