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航天器在近地圆轨道上绕地球运行，以下说法中正确的是（ ） A.航天器的运行速率不变，速率大小均由轨道半径确定 B.放在航天器地板上的物体对地板的压力等于物体所受到的万有引力 C.航天器中的物体处于完全失重状态 D.在航天器中用天平测量一物体质量，左盘放物体，右盘放砝码，当砝码质量不等于物体质量时，天平横梁发生倾斜Laptop computers are popular all over the world. People use them on trains and airplanes, in airports and hotels. These laptops connect people to their workplace. In the United States today, laptops also connect students to their classrooms.Westlake College in Virginia will start a laptop computer program that allows students to do schoolwork anywhere they want. Within five years, each of the 1500 students at the college will receive a laptop. The laptops are part of a ＄10 million computer program at Westlake, a 110-year-old college. The students with laptops will also have access to the Internet. In addition, they will be able to use e-mail to “speak” with their teachers, their classmates, and their families. However, the most important part of the laptop program is that students will be able to use computers without going to computer labs. They can work with it at home, in a fast-food restaurant or under the trees—anywhere at all!Because of the many changes in computer technology, laptop use in higher education, such as colleges and universities, is workable. As laptops become more powerful, they become more similar to desktop computers. In addition, the portable computers can connect students to not only the Internet, but also libraries and other resources. State higher-education officials are studying how laptops can help students. State officials are also testing laptop programs at other universities, too.At Westlake College, more than 60 percent of the staff use computers. The laptops will allow all teachers to use computers in their lessons. As one Westlake teacher said, “Here we are in the middle of Virginia and we’re giving students a window on the world. They can see everything and do everything.”1.The main purpose of the laptop program is to give each student a laptop to _______.A. use for their schoolworkB. access the InternetC. work at homeD. connect them to libraries2.Which of the following is true about Westlake College?A. All teachers use computers.B. 1500 students have laptops.C. It is an old college in America.D. Students there can do everything.3.A window on the world in the last paragraph means that students can _______.A. attend lectures on information technologyB. travel around the worldC. get information from around the worldD. have free laptops4.What can we infer from the passage?A. The program is successful.B. The program is not workable.C. The program is too expensive.D. We don’t know the result of the program yet.