题目

In the past hundred years a million people have died in earthquakes，another million have been killed by hurricanes (飓风)and tornadoes(龙卷风)and 9 million have lost their lives in floods.In addition to this, many more millions  have died as a result of hunger and disease.We should also not forget in many of the world’s countries drought(旱灾)and serious water shortage are a fact of life，especially in the African Shale area bordering(与……接壤)the Sahara Desert. Scientists and engineers around the world have made great advances in earthquake engineering.It_is,_of_course，i汽车拉着拖车在水平道路上沿直线加速行驶，根据牛顿运动定律可知（　　）A．汽车拉拖车的力大于拖车拉汽车的力B．汽车拉拖车的力等于拖车拉汽车的力C．汽车拉拖车的力小于拖车受到的阻力D．汽车拉拖车的力等于拖车受到的阻力