题目

America’s No.1 health problem? A report published by the American Institute of Stress claims the biggest threat to health today is neither cancer nor AIDS. The report says: “It has been estimated that 75—90 percent of all visits to primary care physicians are for stress related problems.”    It is no exaggeration to say that people today are being attacked by stress. According to the National Consumers League, “Work is the top source of stress for adults who have problems and stress in their lives （39%）, followed by family （30%）. Other sources include health （10%）, co14．解比例．9：x=$\frac{5}{16}$$\frac{9}{8}$=$\frac{x}{12}$x：$\frac{5}{2}$=$\frac{1}{5}$：$\frac{1}{20}$．