问答题

Lung Cancer The death rate due to cancer of the lungs has increased more than 800 percent in males and has more than doubled in females during the last 25 years. It is considerably higher in urban and industrial areas than in rural districts. 【B1】______Those factors which have been mentioned most frequently are the presence of foreign particles and other irritants in the air(smoke particles, smog,exhaust fumes),and the smoking of cigarettes and cigars. 【B2】______Among heavy smokers—21 to 30 cigarettes per day—the mortality rate from lung cancer is nearly 17 times the rate from nonsmokers. It is expected the death rate among women will increase as the present high rate of smoking among women has its effect. Sometimes cases of lung cancer are discovered at the time an X-ray is taken for the purpose of detecting tuberculosis. 【B3】______Early detection is absolutely essential if any possibility of cure is to be maintained. Modern X-ray machines in competent hands pose such slight danger, at least to those over 40 years of age, that this would be much more than offset by the advantages of discovering a tumor while it is small enough to be completely removed. 【B4】______The tumor may grow until the bronchus is blocked, cutting off the supply of air to that lung. The lung then collapses, and the secretions trapped in the lung spaces become infected, with a resulting pneumonia or the formation of a lung abscess. 【B5】______The only treatment that offers a possibility of cure, before secondaiy growths have had time to form, is to remove the lung completely. This operation is called pneumonectomy. Malignant tumors of the stomach, the breast, the prostate gland and other organs may spread to the lungs,causing secondary growths.A A common form of lung cancer is bronchogenic carcinoma, so-called because the malignancy originates in a bronchus.B Lung cancer,also known as carcinoma of the lung or pulmonary carcinoma,is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung.C Too often, however, a current emphasis upon the danger of exposure to radiation from X-ray machines can frighten people away from routine chest X-rays and thus prevent an early diagnosis of lung cancer.D Numerous studies have demonstrated a striking correlation between the death rate from lung cancer and smoking habits.E Such a lung cancer can also spread to cause secondary growths in the lymph nodes of the chest and neck as well as in the brain and other parts of the body.F There are many possible causes, but it is still controversial which are most blameworthy. 【B4】