题目

一火车以2m/s的初速度，0.5m/s2的加速度做匀加速直线运动，求： （1） 火车在第3 s末的速度是多少？ （2） 在前4 s的平均速度是多少？ （3） 在第5 s内的位移是多少？ 答案：解：根据公式 v=v0+at 可得 v=(2+0.5×3)m/s=3.5m/s 解：第4s末的速度 v'=(2+0.5×4)m/s=4m/s ；在前4 s的平均速度 v¯=v0+v′2=3m/s 解：第5s内的位移等于前5s的位移减去前4s的位移，故根据公式 x=v0t+12at2 可得 x5=(2×5−12×0.5×52)−(2×4−12×0.5×42)=4.25m You must know Zhong Nanshan. He is a member of the Chinese Academy of Engineering(中国工程院院士) and a doctor in Guangdong,. He_______ many people’s lives in 2003.In 2003, SARS broke out in Guangdong. Later, _______spread（传播） across China and other parts of the world. Patients（病人）_______a lot and got fevers. Some of patients died . Even many doctors and_______got SARS when they treated （治疗）patients.______ everyone was afraid of it. But Zhong Nanshang decided to fight SARS. He spent days and nights on this work. And with his way of treating, many patients began to get ______ . He finally won people’s trust.This year , COVID-19( 新冠肺炎）_______Wuhan. Zhong Nanshan, an 84-year-old man , led (带领）his team to Wuhan to fight COVID-19. He _______people to wear masks, _________hands frequently (频繁地), stay at home and not to go to _____places.“I am just a doctor.” Zhong Nanshan says. But we think he is a hero（英雄）and a fighter（战士）.【1】A.helpedB.savedC.likedD.influenced【2】A.itB.heC.sheD.they【3】A.catchB.caughtC.coughD.coughed【4】A.teachersB.farmersC.nursesD.policemen【5】A.SoB.UntilC.AlthoughD.Because【6】A.worseB.betterC.nervousD.interesting【7】A.hitB.will hitC.hittingD.to hit【8】A.arguedB.allowedC.advisedD.controlled【9】A.carryB.foldC.shakeD.wash【10】A.quietB.crowedC.strongD.strange