相同点：都表示转折，都可以连接两个句子

不同点: ①but还可连接两个并列的成分，however不能;

②however可置于句首，句中，句末，而且在句中时前后用分号或逗号隔开的情形较多。but往往置于句首，无需用标点符号与句子隔开。

2，although与 while

相同点：都是连词，都可引导让步状语从句;

不同点：①although意为“虽然，尽管”，相当于though，所引导的句子通常置于句首。含although从句的复合句可以转化为由but引导的并列句，但although与but不能同时出现;②while意为“然而，但是”，可用作并列连词，表示前后的对比，一般不与but转换，所引导的句子不能置于句首。

Step 3 Practice

a. 用 but， and 和 however 填空：

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

2. I'm sorry， ________ I won't be able to come tonight.

3. We must finish the job in time ________ hard it is.

4. They will supply food ________ drink on Saturday.

5. It looked like rain. ________， it is clear now.

6. Building has started ______ the project will be finished by 2000.

Suggested answers:

1.       however 2. but 3. however 4. and 5. However 6. and

b. 用but, however, while, although 填空。

1. I can not speak Russian ______ my little daughter can.

2. I think there may, ______, be some other reasons we don’t know about.

3. My brother decided to go to that dangerous place, _____ I asked him not to.

4. The boy had said he wouldn’t do it again, ______ he broke his promise.

5. He didn’t turn on the light, _____ it was very dark in the room.

Suggested answers:

1.       while  2. however  3. although  4. but  5. although

Step 4 Vocabulary and listening

a. Pre-listening

Check the meaning of the following words.

Construction  crowded   fascinating   freeway

Huge    inhabitants   similarity    unfortunate

Now answer the questions:

1)      Which words can be used to describe a city?

2)      Which word is connected with building?

3)      Which word means the opposite of difference?

4)      Which word do we use to say that something is sad?

5)      Which word describes the people who live in a particular place?

6)      Which word means a wide road on which cars can travel fast?

Suggested answers:

1.       crowded, fascinating, huge

2.       construction

3.       similarity

4.       unfortunate

5.       inhabitant

6.       freeway

b. While-listening