第三篇 Natural Medicines Since earliest days, humans have used some kinds of medicines. We know this because humans have survived. Ancient treatments for injury and disease were successful enough to keep humans from dying out completely. They were successful long before the time of modern medicine. Before the time of doctors with white coats and shiny(发亮的)instruments. Before the time of big hospitals with strange and wonderful equipment. Many parts of the world still do not have university-educated doctors, Nor do they have expensive hospitals. Yet injuries are treated. And diseases are often cured. How By ancient methods. By medicines that might seem mysterious, even magical(有魔力的). Traditional medicines are neither mysterious nor magical, however. Through the centuries, tribal (部族的)medicine men experimented with plants. They found many useful chemicals in the plants. And scientists believe many of these traditional medicines may provide the cure for some of today’s most serious diseases. Experts say almost 80% of the people in the world use plants for health care. These natural medicines are used not just because people have no other form of treatment. They are used because people trust them. In developed areas, few people think about the source of the medicines they buy in a store. Yet many widely used medicines are from ancient sources, especially plants. Some experts say more than 25% of modern medicines come, in one way or another, from nature. Scientists have long known that nature is really a chemical factory. All living things contain chemicals that help them survive. So scientists’ interest in traditional medicine is not new. But it has become an urgent concern. This is because the earth’s supply of natural medicines may be dropping rapidly. What do the majority of the people in the world use fox health care
A. Strange and wonderful equipment.
B. Factory-produced chemicals.
C. Modern medicines.
D. Plants.
第二篇 TV Goes Digital Coming soon to your TV: views of the hottest live basketball plays from any seat in the stadium. What a better look at that three-point shot Call for a replay from behind the basket. Or better yet, follow the "view" of the ball as it goes through the net. While watching, you might use a built-in speakerphone to talk with a fan in the stands. Or send the score via email to your father in Japan. Sounds impossible It won’t be when the computerized television industries combine to create digital TV machines that receive, send, store, and manipulate TV programs the way computers now manipulate other data; Industry and government representatives recently reached an agreement on how this technology will take place. New digital TVs that allow current TVs to receive digital signals may hit stores by next spring. To understand how the digital revolution will change the way you watch TV it helps to know how TVs work now. Today, TV networks such as CBS and Fox broadcast; TV shows as analogue electrical signals; These signals travel via the airwaves, satellites; or cable as a continuous stream of electromagnetic energy (like light and radio waves). But this system leaves a lot of room for error. The main problem is that interference can change the voltage of the signal as it travels. This may result in a distorted or miscolored picture. If we send out the signal in a form that is nearly free from interference-binary(两位数的)code, pictures and colors are not distorted. you’ll need to buy a new TV to receive these signals. And the new sets may cost 1,000 US dollars more than today’s TVs. But they’ll come with other benefits that may make the price worthwhile. For one thing, the screens will be wider, like movie screens. In addition, the color will be richer. And you’ll also get digital CD-quality sound. Besides these benefits, digital TVs can offer you a much wider choice of programs. Digital data can expand TV choices because computers can compress digital signals. Broadcasters will be able to send six times as much information on the same "channel". The last paragraph says that ______.
A. you can view more programs with a digital TV
B. a football game can be shot with 20 cameras
C. everything you want will appear on the screen
D. broadcasters should consider it their duty to send out different versions of the same program for custom-viewing