Read the following article and select the best answer. Article: What will power your house in the future? According to scientists at the Massachusetts Institute of Technology (MIT) in the US, it might be artificial leaves. Natural leaves can change sunlight and water into energy. It is known as photosynthesis . Now researchers have found a way to imitate this process. The artificial leaf developed by Daniel Nocera and his colleagues at MIT can be seen as a special silicon chip with catalysts . Similar to natural leaves, it can split water into hydrogen and oxygen when put into a bucket of water. The hydrogen and oxygen gases are then stored in a fuel cell, using those two materials to produce electricity, located either on top of a house or beside the house. Though the leaf is shaped like a poker card, scientists stated that it is promising to be an inexpensive somtoe of electricity in developing countries. "One can imagine villages in India and Africa not long from now purchasing an affordable basic power system based on this technology," said an American scientist, Docera. An artificial leaf is not a new idea. The first artificial leaf was invented in 1997 but too expensive and unstable for practical use. The new leaf, however, is made of cheap materials, easy to use and highly stable. In laboratory studies, Nocera showed that an artificial leaf could operate continuously for at least 45 hours. The wonderful improvements come from Nocera's recent discovery of several powerful new, inexpensive catalysts. These catalysts make the energy transformation inside the leaf more efficient with water and sunlight. Right now, the new leaf is about 10 times more effective at carrying out photosynthesis than a natural one. Besides, the device can run in whatever water is available. Hopefully, each home could possible have the access to the new application in the future. Question: The purpose of this article is to _ . - promote the new product - ask people to do the research - introduce a new kind of energy - show the process of photosynthesis
introduce a new kind of energy

Read the following article and select the best answer. Article: Eco City Farms are becoming more popular in cities and towns around the Unites States. Eco City Farms in Edmonton, Maryland, is located near shopping centers, car repair shops and homes. The neighborhood is a working-class community . People do not have very much money. And they have limited access to fresh food in markets. Over the past two years, the farm has attracted volunteers from the community like Marcy Clark. She schools her four children at home. On a recent day she brought them to Eco City Farms for a lesson. Her son Alston Clark thinks his experience is very valuable."I like coming out here,"he says,"You know, you connect with the earth, where your food comes from. You appreciate the food a little bit more." Margaret Morgan started Eco City Farms. She thinks of it as a place where people can learn to live healthier lives. "Growing food in a community brings people together,"she continues,"Every piece of what we do here is a demonstration to show people everything about how to have an eco-friendly community."she says. From the Eco City Farms people come to know that they are not only growing food and raising chickens and bees, but improving the soil with compost made from food waste. Eco City Farms is an experimental operation. The farm gets its power not from the local electricity networks, but from the sun with solar panels. In winter, the green house use a geothermal system. Vegetables can be grown all year. So once a week, all winter long, neighbors like Chris Moss and her three children bike to the farm to pick up a share of the harvest. "I like eating the vegetables "say five-year-old Owen Moss. Question: What is the author's attitude toward Eco City Farms? - Enthusiastic . - Disappointed. - Surprised. - Doubtful.
Enthusiastic .

Q: Read the following article and select the best answer. Article: 'As I stood in front of the grave of President Richard Nixon, I was thinking about the time 25 years ago when this president helped bring the United States and China closer together. Young people of our two countries should help this relationship grow.' This remark was made by a Shanghai student when speaking to his fellow students at the Nixon Library in California, U.S.A. He was one of 80 middle school students from China attending a month-long 'Youth Summit'. The Summit was to mark the 25th anniversary of President Nixon's journey to China, which was the turning point in China-U.S. relations. The Youth Summit was aimed at increasing understanding and friendship between young students of the two countries through visits and discussions. Seventy-five American students were selected to visit China. They also visited the Nixon Library on July 21 before leaving for Beijing the next day. The head of the Library said he was pleased to see the American and Chinese students talking and laughing together. One Chinese student said, 'I didn't find it particularly difficult to talk with Americans. We have our differences, but we have a lot in common. Dialogue is good for us.' Question: The words 'Youth Summit' in the text refer to _ . - visits to the Nixon Library - the Chinese students' visit to the U.S. - a meeting discussing relations between China and the U.S. - activities to make the ties between the Chinese and American students stronger
A: activities to make the ties between the Chinese and American students stronger

Read the following article and select the best answer. Article: If music makes you smarter, and exercise helps brain function, can exercising to music really boost brainpower? Some researchers said it could. Volunteers who listened to Vivaldi~ "Four Seasons" while working out on a treadmill did much better on a test of verbal ability than when they exercised without music, a team at prefix = st1 /OhioStateUniversityfound. "Evidence suggests that exercise improves the cognitive performance of people with coronary artery disease ," said psychologist Charles Emery, who led the study. "And listening to music is thought to enhance brainpower. We wanted to put the _ together," Emery added in a statement. Writing in the latest issue of the journal Heart & Lung, Emery and colleagues said they studied 33 men and women taking part in a cardiac rehabilitation program after having bypass surgery, angioplasty or other procedures to treat clogged arteries. The volunteers said they felt better emotionally and mentally after working out with or without the music. But their improvement on the verbal fluency test doubled after listening to music on the treadmills ."Exercise seems to cause positive changes in the nervous system, and these changes may have a direct effect on cognitive ability," Emery said. "Listening to music may influence cognitive function through different pathways in the brain. The combination of music and exercise may stimulate and increase cognitive arousal while helping to organize cognitive output." Emery said he now wanted to test people using music of their own choice. "We used The Four Seasons' because of its moderate tempo and positive effects on medical patients in previous research," Emery said. "But given the range of music preferences among patients, it's especially important to evaluate the influence of other types of music on cognitive outcomes." Question: We can infer that Emery's next step will be - to let the volunteers to listen to music of their own choice - to choose volunteers of different ages - to let the volunteers to listen to moderate tempo music - to test whether music can help recovery
to let the volunteers to listen to music of their own choice