题目

Climate change will increase US wildfires,and the smoky air will cause terrible problems in areas far beyond those burned,reports an environmental group Thursday. Two-thirds of Americans,or nearly 212 million,lived in states suffering from wildfire smoke three years ago,according to the report by the Natural Resources Defense Council(NRDC).These areas,which had smoke for at least a week,were nearly 50 times greater than those burned directly by fire. “It affects a much wide area of the United States than people have realized.” says author Kim Knowlton,a Columbia University health p有5筐菜，以每筐50千克为准，超过的千克数记为正，不足记为负，称重记录如下： ＋3，－6，－4，＋2，－1，总计超过或不足多少千克？5筐蔬菜的总重量是多少千克？