Developing and Developed Countries
②however可置于句首，句中，句末，而且在句中時前后用分號或逗號隔開的情形較多。but往往置于句首，無需用標點符號與句子隔開。
2，although與 while
相同點：都是連詞，都可引導讓步狀語從句；
不同點：①although意為“雖然，盡管”，相當于though，所引導的句子通常置于句首。含although從句的復合句可以轉化為由but引導的并列句，但although與but不能同時出現；②while意為“然而，但是”，可用作并列連詞，表示前后的對比，一般不與but轉換，所引導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 .
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
1. listen to the conversation and tick the topics you hear.
climate industry location pollution population
safety tourism transport wealth
suggested answers:
the only topic they don’t cover is location
2. listen to the tape again. and tick the statements you think are true.