3. Discuss in pairs and answer the following questions. 1. What do you think of chewing gum? Is it good or bad for you? 2. Do you or your friends /family buy it? Why? 3. What do you do after chewing it?

4. Look at the title of the magazine article and predict which issues may be covered in the article. Then read the article quickly and see if any of your guesses are right? It is about whether chewing gum is good or bad for you.

5.  Read the text quickly and divide it into four parts, then summarize the main topic of each part.  Part 1(paragrah --- )  Part 2(paragraph --- )  Part3(paragraph --- )  Part4(paragraph --- )

7. Advantage Advantage Disadvantage Disadvantage Helping people: 1._________ bad breath 2. ____________ tooth decay 3._______weight 4. __________ smoke 1.making digestions __________________ 2. Causing feelings of __________________ 3. Leading to _________ ______________ 4. Making people neglect_____________ _____________________

8. 1.How serious is the problem of bad breath? 2.What is added to sugar-free chewing gum which may help prevent tooth problems? 3.According to one research project, what is one way of burning 70 kilocalories? 4.What would be the effect on the stomach of constant chewing? 5.What other activities are stated that are better than chewing gum?

9. Match the conditional sentences in italics in the text with the following types: 1.zero conditional 2.1st conditional 3.2nd conditional 4.3rd conditional Which of the sentences in italics talk about the past, the present and the future?

10. Read the sentences. Do they describe situations that are: a)True or could possibly happen? b)Imaginary, unreal or contrary to facts?

11.  If he has time, he will come.  We won’t succeed unless we plan well.  (unless= if---not)  从句用一般现在时或现在完成时， 主句用一般 将来时

12.  If I were a millionaire, I would buy a big house.  If I were the girl in the story, I would call the police at once.  Tomorrow I will go to USA. If I were in China, I would make dumplings with you. 表示与现在或将来事实相反 从句主句 过去式 would + V 原

13.  I was on my own yesterday. If they had invited me, I would have gone to the party.  I went to library yesterday. If I had went to the concert, I would have taken photos with the singers.  He had traffic accident yesterday. If he had driven more carefully, he would have arrived home safely. 表示与过去事实相反 从句主句 had done would have done

14.  如果过去天气好一些， 现在庄稼还会长得 更好。  If the weather had been more favourable, the crops would be growing still better.  ( 注意：白字代表过去， 黄字代表现在或将 来 )

15.  要是大夫昨晚来得早一点， Amy 今天还活 着。  If the doctor had come sooner last night, Amy would be alive today.  如果他多得六票， 他现在就是我们的主席。  If he had received six more votes, he would be our chairman now.

16. 与现在，将来事实相反与过去事实相反 从句 If + 主语 + 过去式 If + 主语 + had done 主句 主语 + would +V 原 主语 + would have done

17. 从句主句 与现在 或将来 相反 If + 主语 + 一般 过去式 主语 + would+ V 原 与过去 相反 If + 主语 + 过去完 成时 主语 + would + have done

18.  1. If you ____ at school, you ____ a college student now.  A. had studied hard; would have been  B. should have studied hard; should have been  C. had studied hard; would be  D. would study hard; must have been

19.  2. ____ you ____ to the teacher, you ___ how to use the idioms now.  A. Had, listened, would know  B. If, listen, know  C. If, had listened, would have known  D. Had, listened, know

20.  3. If he missed the bus, he _____ to school on foot.  A. would go B. went  C. would have gone D. had gone  4. Had I known her name, ______.  A. or does she know mine  B. she would come here  C. I would have invited her to lunch  D. she had come

21.  5. ---Did you hear what Jack said to his parents?  ---Yes, and I ____ talk that way if I ____ Jack.  A. won’t, am B. wouldn’t, were  C. couldn’t, were D. didn’t, were

22.  6. He ___ you if you ____ to see him this afternoon.  A. might tell, went  B. might tell, are going  C. might have told, went  D. should tell, will have gone

23.  7. It ____ a different matter now if you ____ his advice.  A. is, had followed B. was, followed  C. might be, had followed  D. might be, followed  8. The soldier died in the hospital. He ___ if the doctor ____ on him two hours before.  A. might be saved, operated  B. could have been saved, had been operated  C. could be saved, had operated  D. could have been saved, had operated

24.  ---If he ___, he ____ that food.  ---Luckily he was sent to the hospital immediately.  A. was warned; would not take  B. had been warned; would not have taken  C. would be warned; had not taken  D. would have been warned, had not taken

25.  I didn’t see your sister at the meeting. If she ____, she would have met my brother.  A. has come B. did come  C. came D. had come  You didn’t let me drive. If we ____ in turn you _____ so tired.  A. drove; didn’t get B. drove; wouldn’t get  C. were driving; wouldn’t get  D. had driven; wouldn’t have get