题目

 跳伞运动员做低空跳伞表演，他离开飞机后先做自由落体运动，当距离地面 125 m时打开降落伞，伞张开后运动员就以14.3 m/s2的加速度做匀减速运动，到达地面时速度为5 m/s，问：（1）运动员离开飞机时距地面的高度为多少?（2）离开飞机后，经过多少时间才能到达地面?（g=10 m/s2）      答案： 305m 6.7s  1During the First World War, some Americans indirectly benefited because of the war. With two million white men fighting in Europe and no new immigrants entering the country, many jobs in the United States became available to blacks and women for the first time.2Both groups proved their ability to do any kind of job. Women became railway conductors, brick layers, and factory workers. Their presence in traditionally male workplace produced many problems. Men were annoyed by women’s higher productivity and willingness to work for lower pay. Working mothers were often criticized for leaving their families. But many women welcomed the responsibilities. “It was not until our men were called overseas,” said one woman bank executive, “that we make any real onslaught on the realm of finance, and became tellers, managers of departments, and junior and senior officers.”3Women who did not take jobs helped in the war effort in other ways. They made uniforms, rolled bandages, and campaigned for the sale of Liberty Bonds to help finance the war. 4American manufacturers offered jobs to large numbers of black Americans for the first time as a result of the war. Most factories were located in the North. To take advantage of these new job opportunities, many black families moved from their homes in the South to the Northern cities such as Pittsburgh, Cleveland, Buffalo, Chicago, and Detroit.5White Americans were of two minds about the role of black Americans in the war effort. On the one hand, black workers’ ability to learn new jobs quickly and do them well strengthened the home front, and the black men’s fighting ability helped the Allies win the war. However, many whites did not want to acknowledge that blacks were capable, effective workers. White soldiers returning from the war had no desire to compete for jobs with blacks on equal terms. At the same time, many blacks were not willing to a lesser role once the war had ended. 【小题1】Why could American women and backs find jobs during World War I?A．They were taken to serve the war.B．They had their equal right at that time.C．Workforce was in great need.D．They had better productivities.【小题2】Which of the following is Untrue according to the above passage?A．Blacks women were not allowed to fight in World War I.B．All American women went to work during World War I.C．Northern cities applied more blacks during World War I.D．Women and blacks earned a lot during World War I.【小题3】Which of the following is the main idea of the whole passage?A. Americans benefited a lot from World Ward I.B. World War I had strong effect on America.C. Some Americans benefited from World War I indirectly.D. U.S.A. women and blacks contributed much in World War I.【小题4】Which of the following shows the right structures of the above passage?A．1→23→45B．1→2→3→4→5C．1→23→4→5D．123→4→5