What do the common cold, the flu, and AIDS have in common? They are all diseases caused by viruses, tiny microorganisms that can pass from person to person. It is no wonder that when most people think about viruses, finding ways to _ them is what is on people's minds. Not everyone runs from the tiny disease carriers, though. In Cambridge, Massachusetts, scientists have discovered that some viruses can be helpful in an unusual way. They are putting viruses to work, teaching them of the world's smallest rechargeable batteries. Viruses and batteries may seem like an unusual pair, but they are not so strange for engineer Angela Belcher, who first came up with idea. At the Massachusetts Institute of Technology in Cambridge, she and her team bring together different areas of science in new ways. In the case of the virus-built batteries, the scientists combine what they know about biology, technology and production techniques. Belcher's team includes Paula Hammond, who helps put together the tiny batteries, and Yet-Ming Chiang, an expert on how to store energy in the form of a battery. Many batteries are already pretty small. However, every year, new electronic devices like personal music players or cellphones get smaller than the year before. As these devices become smaller, ordinary batteries won't be small enough to fit inside. The ideal battery will store a lot more energy in a smaller package than ordinary batteries. Right now, Belcher's model battery, a metallic disk completely built by viruses, looks like a regular watch battery. But inside, its parts are very small--- so tiny that you can only see them with a powerful microscope. How small are these battery parts? To get some idea of the size, pluck one hair from your head. Place your hair on a piece of white paper and try to see how wide your hair is--- pretty thin, right? Although the width of each person's hair is a bit different, you could probably fit about 10 of these virus--- built battery parts, side by side, across one hair. These... According to the passage, virus-built batteries _ . A) have been used in many electronic devices now B) may arouse ordinary people's resistance C) may be helpful in curing some diseases D) have more advantages than traditional batteries
D
When a storm is coming, most people leave the area as quickly as possible and head for safety. But there are a few people who will get into their cars and go straight for the center of the storm. These people are willing to risk being killed by floods or 100-kilometer-an-hour winds for the excitement of watching the storm close up. "Storm chasing " is becoming an increasing popular hobby, especially in the Midwest of the United States, where there are frequent storms between March and July. A storm chaser begins the day by checking the Internet for the latest weather report, and then drives up to 1000 kilometers to where the storm will be and waits for it to develop. Although anyone can do it, storm chasing is extremely dangerous. The power of a big storm can throw a cow into the air or destroy a whole house in seconds. Storm chasers are also often hurt in accidents caused by driving in a heavy rain. If you are a beginner, it is much safer to join a group for storm-chasing vacations during the storm season. Even then, storm chasing is not all adventure and excitement. "Storm chasing is 95% driving," says Daniel Lynch, who spends most of his summer storm-chasing. "Sometimes you can sit around for hours waiting for something to happen, and all you get is blue sky and a few light showers." However, for storm chasers, it is all worth it. "When you get close to a storm, it is the most exciting sight you will ever see in your life," says Jasper Morley. "Every storm is an example of the power of nature. It is the greatest show on earth." Beginners of storm chasing are advised _ . A) not to drive in a heavy rain B) to do it in an organized way C) not to get too close to a storm D) to spend more time on it in summer
B
Q: Houses fall down. Trees fall over. Large holes form in the ground. Could Alaska be sinking? That's what some villagers in Alaska have been asking themselves recently--and scientists think they know why. Warmer temperatures may be causing Alaska's frozen ground to thaw . About 85 percent of Alaska's land surface has _ . Permafrost supports the ground above it--including trees, houses, and roads. But why is the permafrost thawing? Some scientists say that human-caused pollution is leading to global warming. And most scientists agree that Alaska has been getting warmer. They say that the warmer temperature is causing permafrost to thaw in some areas. The thawing permafrost can cause problems for people, plants, and animals. "The collapsing is a problem in the villages in Alaska which are built on permafrost, and some of them may have to move to safer ground, where there is no permafrost," Weller said. The Alaskan town of Glennallen saw its old post office collapse. And, according to James Walters, a permafrost expert at the University of Northern Iowa, house-moving companies have been very busy. "Melting permafrost can also destroy trees and forests," Weller said. "When holes in the ground form, trees fall into them and die. This could turn a forest into a swamp , and animals which need the forest will have to move elsewhere." The melting could cause "severe problems." Weller says: "This could take hundreds of years, but in the end Alaska will look quite different from what it looks like now." Houses in the villages fell down because _ . A) they were not strong enough B) the weather was warmer C) they were built on permafrost D) the ice had melted
A: C
(Question)
Americans get some of their news and entertainment from public television and radio. These public media receive money to operate from private citizens, organizations and government. Many of their programs are educational. But most of the American media are run by businesses for profit. These privately owned media have changed greatly in recent years. Newspapers, magazines and traditional broadcast television organizations have lost some of their popularity. At the same time, online, cable and satellite media have increased in numbers and strength. So have media that serve racial groups and those communicating in foreign languages. In general, more media than ever now provide Americans with news and entertainment. At the same time, fewer owners control them. Huge companies have many holdings . In some areas, one company controls much of the media. One dramatic change in American media is the increased success of cable television. It comes into most homes over wires. It does not use the public airwaves to present programs, as broadcast television does. Like broadcast television, most cable television programs perform advertisements. This is true although people must pay to see cable television in their homes. Thirty years ago, few people had cable. Today, about sixty-eight percent of American homes have cable television. Television by satellite also is gaining popularity. Over the years, traditional broadcast organizations have tried to appeal to as many watchers as possible. Many cable companies, however, present programs for one special group of viewers. For example, there are cable stations for people who like books, cooking, travel, golf or comedy. Which of the following is true about American public media? A) They depend on the government. B) They are controlled by the government C) They are free D) They can earn money.
(Answer)
D