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 com （查看全部）
