题目

现在高速公路上的标志牌都用“回归反光膜”制成。夜间行车时，它能把车灯射出的光逆向返回，标志牌上的字特别醒目。这种“回归反光膜”是用球体反射元件制成的，反光膜内均匀分布着一层直径为10mm的细玻璃珠，所用玻璃的折射率为，为使入射的车灯光线经玻璃珠折射——反射——折射后恰好和入射光线平行，如图所示，那么第一次入射的入射角应是A．15°           B．30°            C．45°         D．60° We don’t know how different our life will be in the future. We can only try to imagine it. At first we think about human relationship. In the year 2050, we will use computers almost every day. We will make new friends through the Internet—even our husbands or wives will be met in this way. It will be much faster and easier for us. On the other hand, our relationships with people won’t be as important as they are today-we will feel a little lonely. Computers will also help us in many other activities in 2050. For example, they will be used by the children at school to make their learning easier. In addition, there will be much more other machines which will play a similar role as computers, like robots which will do the housework for us. Spending holidays will also be completely different. Traveling to other planets or to the moon will be available for everyone. Means of transport will, of course, change, too. We will use solar-powered cars, which will be much more environmentally friendly. We could expect that the faster technological progress would lead to a more polluted environment. But it isn’t true. We will pay more attention to protecting the environment. And, scientists will probably find cures for many dangerous diseases, like cancer or AIDS. Therefore, our surroundings as well as health will be in better condition. Although we can’t predict the exact changes which will be made in the world, we often think about them. We worry about our and our children’s future; we have expectations, hopes as well as fears. But I think we should be rather sanguine about our future. We should be happy and believe good things will happen1.Why will people probably feel a little lonely in 2050?A.Because the number of people will become much smallerB.Because there will be less face-to-face communicationC.Because people won’t like making friends with each otherD.Because people won’t communicate with each other much often2.The third paragraph mainly tells us ________A.computers will do all the things for human beingsB.how people will use computers to communicate with each otherC.machines like computers and robots will help people a lotD.how people will use robots to do the housework3.According to the passage, which of the following will happen in 2050?A.The relationship between people will be more important than that of todayB.The way of spending holidays will be the same as that of todayC.It won’t be difficult for people to travel to other planetsD.Our environment will be much more polluted with a growing number of cars4.What does the passage mainly talk about?A.How people will communicate in the year 2050B.What our life will be like in the year 2050C.How people will travel and spend their holidays in the year 2050D.What high technology will appear in the year 2050