Part A

　　Directions:

　　Read the following four texts. Answer the questions below each text by choosing A, B, C or D. Mark your answers on ANSWER SHEET 1.  (40 points )

　　Text 1

　　Commuter trains are often stuffy and crowded, and they frequently fail to run on time. As if that were not bad enough, Tsuyoshi Hondou, a physicist at Tohoku University in Japan, published a paper in 2002 that gave commuters yet another reason to feel uncomfortable. Dr Hondou examined mobile phone usage in enclosed spaces such as railway carriages, buses and lifts, all of which are, in essence, metal boxes. His model predicted that a large number of passengers crowded together, all blathering, sending text messages, or browsing the web on their phones, could produce levels of electromagnetic radiation that exceed international safety standards. That is because the radio waves produced by each phone are reflected off the metal walls of the carriage, bus or lift. Enough radiation escapes to allow the phone to communicate with the network, but the rest bathes the inside of the carriage with bouncing microwaves.

　　This sounds worrying. But maybe it isn't after all. In a paper published recently in Applied Physics Letters, Jaime Ferrer and Lucas Fernández Seivane from the University of Oviedo in Spain-along with colleagues from the Polytechnic University of Madrid and Telefónica Móviles, a Spanish mobile operator-dispute Dr Hondou's findings. They conclude that the level of radiation is safe after all.

　　The key addition to the new research is the effect of the passengers themselves. While each phone produces radiation that bounces around the car, the passengers absorb some of it, which has the effect of reducing the overall intensity, just as the presence of an audience changes the acoustics of a concert hall, making it less reverberant. Dr Hondou's model, in short, was valid only in the case of a single passenger sitting in an empty carriage with an active mobile phone on every seat.

　　While Dr Hondou acknowledged this in his original paper, he did not specifically calculate the effect that leaving out the other passengers would have on the radiation level. As a result, say the authors of the new paper, he significantly overestimated the level of electromagnetic radiation. When one is sitting on a train, Dr Ferrer and his colleagues found, the most important sources of radiation are one's own phone, and those of one's immediate neighbours. The radiation from these sources far exceeds that from other phones or from waves bouncing around the carriage. And all these sources together produce a level of radiation within the bounds defined by the ICNIRP, the international body that regulates such matters.

　　21. According to paragraph 1, the essential common characteristic of train carriages, buses, and lifts is that

　　[A] they are all metal boxes.

　　[B] they are often stuffy and overcrowded.

　　[C] they all allow enough radiation to escape for mobile communications to take place.

　　[D] people use their mobile phones in them.

　　22. How could "levels of electromagnetic radiation that exceed international safety standards" be produced?

　　[A] Mobile phones give off a lot of electromagnetic radiation.

　　[B] Train carriages, buses, and lifts are not safe places to use mobile phones.

　　[C] A lot of people could use their mobile phones in a confined space at the same time.

　　[D] Blathering produces radio waves which bounce around the interior of these places.

　　23. Why do the Spanish researchers dispute Dr. Hondou's theory?

　　[A] Because they are funded by a mobile phone operator.

　　[B] Because people absorb electromagnetic radiation.

　　[C] Because electromagnetic radiation isn't dangerous at all.

　　[D] Because Dr. Hondou assumed that every single person was using their mobile phone at exactly the same time.

　　24. Dr. Hondou's research was not thorough enough because

　　[A] he didn't have enough time to assess everything before his paper was published.

　　[B] he didn't admit that the people in train carriages, buses, and lifts could influence the level of electromagnetic radiation.

　　[C] he didn't investigate the effect of people on electromagnetic radiation levels.

　　[D] Japan is a crowded country where people often use mobile phones, so he only looked at that specific situation.

　　25. According to the Spanish researchers, which of the following statements is true?

　　[A] The closer you are to a mobile phone, the greater your exposure to electromagnetic radiation.

　　[B] The closer you are to a mobile phone that is being used to send and receive signals, the greater your exposure to electromagnetic radiation.

　　[C] The amount of electromagnetic radiation reflected by metal is almost too small to be measured.

　　[D] You shouldn't stand close to people who are using their mobile phones in train carriages, buses, and lifts.