1. but 连词，“但是”。用来引出微弱的反对意见，是口语中的常用词。例如：
I was going to write, but I lost your address.
我本来要写信的，可是把你的地址弄丢了。
2. however ①副词，“可是；不过；然而；无论如何；不论到什么程度”。however比but的词义还要弱些，并不直接引出相反的意见，因此，常用作插入语。例如：
I’d like to go with you; however, my hands are full.
我很想和你一块儿去，可是我忙不过来。
②连词，“不管用什么方法；无论什么方式”。例如：
However I cook eggs, the child still refuses to eat them.
不管我用什么方法做鸡蛋，小孩还是不肯吃。
3.although 连词，“虽然；尽管”。although与though大致相同，口语中though比较常用。例如：
Mr. Hall understands that although maths has always been easy for his son, yet this problem is not easy for him.
Hall先生明白，尽管数学对他儿子来说一直很容易，但这道题对于他来说并不简单。
4. while 连词，“但；却；然而”。它表示对比或相反的情况。例如：
You like sports, while I prefer music.
你喜欢体育，而我更喜欢音乐。
[小试身手]
Ⅰ. 用but，however，although和while填空。
1. , they did not seem to have much effect.
2. He drives not carefully slowly.
3. many difficulties are still ahead, we are determined to make greater achievements.
4. He said that it was so; he was mistaken, .
5. He looks honest, actually he’s a rogue (无赖).
6. He went out for a walk, I stayed at home.
7. cold it is, she always goes swimming.
8. I’m very sorry, I can’t see you today.
Ⅱ. 单项填空。
1. — Someone wants you on the phone.
—nobody knows I am here. [2011年全国I卷]
A. Although
B. And
C. But
D. So
2. regular exercise is very important, it’s never a good idea to exercise too close to bedtime.
[2011年天津卷]
A. If
B. As
C. Although
D. Unless
3. you may have, you should gather your courage to face the challenge. [2010年上海卷]
A. However a serious problem
B. What a serious problem
C. However serious a problem
D. What serious a problem
Key：Ⅰ. 1. However 2. but 3. Although 4. however 5. but 6. while 7. However 8. but Ⅱ. 1. C 2. C 3. C
