简介：
Nature imposes difficult conditions upon the earth from time to time. The tornado and forest fire destroy natural 1 , （resounds homes and other structures, and very often harm or kill people. Technological tragedies happen with little or no warning as we see trains crash and airplanes fall from the sky shortly after take-off. As tragic as calamities are, they seem to 2 （bringout） the best in human nature. People trained in 3 merge care arrive at the scene and begin assisting the injured. Others come with equipment to remove debris. M （查看全部）
