Why Women Live Longer
It is a fact that women live longer than men. That difference was not so obvious a long time ago, because everyone died at an early age, Now, however, an average chinese male is expected to live 71 years; the life expectancy of chinese people is 75 years. The reasons for the difference are very complex, and scientists can only understand some of them.
Disease is chiefly responsible for the difference in life expectancy. At present, heart disease is the main cause of death for men after 40. Doctors have realized that differences in life style and personal habits between men and women are a factor in heart disease. Over the past few decades, men have hud poorer diets, have gotten less exercise and have smoked much more than women. Now studies are also beginning to show that the female sex hormones help to protect women from heart disease. More studies are needed to actually tell scientists how these hormones provide their protection.
It seems clear, then, that natural factors help to explain why women live longer than men do. These natural factors also interact with lite style and personal habits.
The death rate from heart disease has already dripped as men have become more aware of effects of diet, exercise and smoking on their health. Present research may result in a more basic understanding of the natural factors.
这篇议论文不仅结构严谨，而且列举了一些数字，使文章更具说服力。
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