2014英语四级听力练习慢速4.15(2)_大学英语听力

2014英语四级听力练习慢速4.15(2)

　　As bad as those chemicals are, nicotine may be the most threatening of them all. Nicotine is a poison found in tobacco. It gives smokers pleasure and keeps them coming back for more.

　　The body grows to depend on nicotine. Studies have found that nicotine can be as difficult to resist as alcohol or the drug cocaine. Experts say nicotine can kill a person when taken in large amounts. It does this by stopping the muscles used for breathing.

　　So is there any way to smoke without harming your health? The majority of available research suggests not. Smoking even a few cigarettes can be dangerous. But many of the harmful effects of smoking are reversible. They can be undone. That is why most medical experts advise people to stop smoking forever.

　　The American Cancer Society says blood pressure returns to normal 20 minutes after the last cigarette. Carbon monoxide levels in the blood return to normal after eight hours. The chance of heart attack decreases after one day. After one year, the risk of heart disease for a non-smoker is half that of a smoker.

　　E-Cigarette is Still Unproven as Nicotine Replacement

　　There are many products available to help people reduce their dependence on cigarettes. Nicotine replacement products provide the body with small amounts of the chemical through forms other than cigarettes. The amounts of nicotine are slowly reduced over time.