unit 7 B.ppt

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1、Smoking and Cancer Americans smoke six thousand million cigarettes every year(1970 figures).This is roughly the equivalent of 4,195 cigarettes a year for every person in the country of 18 years of age or more.It is estimated that 51%of American men smoke compared with 34%of American women.Since 1939

2、,numerous scientific studies have been conducted to determine whether smoking is a health hazard.The trend of the evidence has been consistent and indicates that there is a serious health risk.Research teams have conducted studies that show beyond all reasonable doubt that tobacco smoking,particular

3、ly cigarette smoking,is associated with a shortened life expectancy.Cigarette smoking is believed by most researchers in this field to be an important factor in the development of cancer of the lungs and cancer of the throat and is believed to be related to cancer of the bladder and the oral cavity.

4、Male cigarette smokers have a higher death rate from heart disease than non-smoking males.(Female smokers are thought to be less affected because they do not breathe in the smoke so deeply.)The majority of physicians and researchers consider these relationships proved to their satisfaction and say,G

5、ive up smoking.If you dont smoke,dont start!Some competent physicians and research workers though their small number is dwindling even further are less sure of the effect of cigarette smoking on health.They consider the increase in respiratory diseases and various forms of cancer may possibly be exp

6、lained by other factors in the complex human environment:atmospheric pollution,increased nervous stress,chemical substances in processed food,or chemical pesticides that are now being used by farmers in vast quantities to destroy insects and small animals.Smokers who develop cancer or lung diseases,

7、they say,may also,by coincidence,live in industrial areas,or eat more canned food.Gradually,however,research is isolating all other possible factors and proving them to be statistically irrelevant.Apart from statistics,it might be helpful to look at what smoking tobacco actually does to the human bo

8、dy.Smoke is a mixture of gases,vaporized chemicals,minute particles of ash,and other solids.There is also nicotine,which is a powerful poison,and black tar.As the smoke is breathed in,all these components form deposits on the membranes of the lungs.One point of concentration is where the air tube di

9、vides.Most lung cancer begins at this point.Smoking also affects the heart and blood vessels.It is known to be related to Beurgers disease,a narrowing of the small veins in the hands and feet that can cause great pain and lead even to amputation of limbs.Smokers also die much more often from heart d

10、isease.While all tobacco smoking affects life expectancy and health,cigarette smoking appears to have a much greater effect than cigar or pipe smoking.However,nicotine consumption is not diminished by the latter forms,and current research indicates a causal relationship between all forms of smoking

11、and cancer of the mouth and throat.Filters and low tar tobacco are claimed to make smoking to some extent safer,but they can only marginally reduce,not eliminate the hazards.equivalent a.(to sth.)equal in value,amount,meaning,etc.相同的nWhat is$5 equivalent to in French francs?五美圆相当于多少法郎？n.thing,amount

12、 or word that is equivalent 相等的数量，事物nIs there a French word that is the exact of the English word“home”?hazard n.(thing that can cause)danger,risknSmoking is a serious health hazard.吸烟严重危及健康nWet roads are a hazard to drivers.道路湿滑会对司机构成危险 v.risk;suggest tentatively,venture to makenRock-climbers are h

13、azarding their lives.冒生命危险nI dont know where he is but I could hazard a guess.我不知道他在哪，但我可以猜猜看 expectancy n.state of expecting or hopingnShe went to meet him with an air of expectancy.n a look/feeling of expectancy expectation n.firm belief,hope;confident feelingnHe has little of winning a prize.nHis

14、 parents have great expectations for his future.nThe holiday was beyond all expectations.nTheres no expectation of snow tonight.expectant a.expecting,hopefuln children with expectant faces waiting for the magician expected a.n expected objections to the planprocess v.put(a raw material,food,etc.)thr

15、ough an industrial of manufacturing process in order to change it;n process leather to make it softer 鞣制皮革使其变得柔软n processed cheese 经加工的干酪（以便保存）n.deal with officially;perform operations on a computernIt may take several weeks for your application to be processed.审查你的申请书也许要等几个星期nHow fast does the new

16、micro process the data?这新微型计算机处理数据有多快？isolate v.put or keep sth.entirely apart from other people or things;separate sb./sth.n isolate a problem(in order to deal with it separately)nThey have successfully isolated the virus causing the disease.deposit n.沉积物，矿床nA thick deposit of mud lay on the fields

17、 when the flood went down.洪水退后，田野上留下一层厚泥nValuable deposits of oil have been found by drilling.通过钻探发现很有开采价值的油层 n.存款，定金，押金nShe made two deposits of$500 last month.nThe shop promised to keep the goods for me if I paid a deposit.nI had to pay a$100 deposit to the landlord before I can move into the hous

18、e.ntube:hollow tube-shaped organ of the body air/bronchial/Eustachian tube 气管，支气管，耳咽管nvessel:tube-like structure in the body of an animal or a plant,conveying or holding blood or other fluid blood-vessels 血管vein n.静脉，特征，气质，风格nRoyal blood ran in his veins.有王族血统nHer stories revealed a rich vein of humor.小说饶有风趣nThe complaints continued in the same vein.总是那一类的牢骚，没完没了The End