Each year, road accidents kill a million people and injure millions more. The economic costs are greatest for developing countries. Earlier this year, the United Nations called for a campaign to improve road safety. One way to avoid accidents is better driving. Another is better roads and bridges. Engineers in the Unites States have designed ten new concrete mixtures that they think could make bridges last longer. Professor Paul Tikalsky leads the experiments by a team at Pennsylvania State University. He says bridges made of concrete now last about twenty-five to thirty-five years. But he says the new mixtures might extend that to seventy-five or even one-hundred years. Concrete is made of stone, sand, water and cement . The materials in the cement hold the concrete together. Ancient Romans built with concrete. Yet strengthened concrete bridges did not appear until the late 1800s. People keep looking for new ways to improve concrete. Professor Tikalsky says it is one of the most complex of all chemical systems. The new mixtures designed by his team contain industrial waste products. He says these make the concrete better able to resist damage from water and salt over time. One of the products is fly ash. This is released into the air as pollution when coal is burned. Professor Tikalsky says particles of fly ash are almost exactly the same size and chemical structure as Portland cement. _ is the most costly material in concrete. So using fly ash to replace some of it would save money. The federal government is paying for part of the research. Engineers anywhere can use the technology. Professor Tikalsky says some of the ideas have already been put to use in China, the Philippines and other countries. Why did the United Nations launch the campaign? A) Because the United Nations wanted to reduce road accidents and economic costs. B) Because two million people were killed in the accidents. C) Because engineers wanted to design ten new concrete mixtures. D) Because the United Nations made bridges of the new mixtures which could last for about 20 to 35years.
A
My transportation was unexpectedly smooth and I arrived at the meeting half an hour earlier. I kept my eyes on the restaurant door. Several customers entered, but not my friend. At 6:00 pm, she sent me a text message: "Urgent work to finish. Will be 20 minutes late." I had left my book in the office, so I spent the time thinking of my experiences of being late in China. On my first visit in 1985, punctuality was deeply rooted in the Chinese hearts. There were no traffic jams then. As a teacher in Canada, I always insisted on punctuality. I would open the classroom door to a late student for the first time and the second, but not the third. During the six years I worked for CCTV, I had a Chinese friend whom I often saw at lunch time, or after work. We used to meet at the subway station nearby. He was always late by 10-20 minutes. To my question, "You were busy?" he would surprisingly answer, " No." Once I asked him to check the clock in his office, he smiled. In March 2015, I got permanent residence in China. The ceremony was scheduled for 9:00 am at the Public Security Bureau on the Second Ring Road. I told my driver I had to get there by 8:40 am. "No problem," he replied. But he thought he had time to drop someone off at the airport before picking me up. I desperately waited for him. Then, to rub salt into my wound, he had to stop at the exit of a gas station. Finally, I entered the room at 9:07 am -- the last guest to arrive! How did the Chinese friend feel when the author asked him to check the clock? A) Excited. B) Embarrassed. C) Satisfied. D) Shocked.
B
Q: When two Bangs meet Sheldon Cooper is a scientific genius on the popular American TV show, The Big Bang Theory (<<>> ). He finally met his match last year: Stephen Hawking. This is not the first time that the scientist has appeared on TV. He has also been on Star Trek (in 1987) and The Simpsons (in 1989). Each time, he played himself. Hawking, 71, is perhaps the world's most famous scientist after Albert Einstein. He has spent his whole life studying the beginning and the end of the universe, including the Big Bang theory. The Big Bang theory explains the early development of the universe. According to the theory, about 13.7 billion years ago everything was all squeezed together in a tiny, tight little ball, and then the ball exploded. The results of that explosion are what we call the universe. Hawking has always tried to make science more popular with people. His book: A Brief History of Time was published in 1988. In the book he shares his understanding of the universe in simple language. The book tries to explain many subjects about the universe to common readers, including the Big Bang, black holes and light cones . Hawking's achievements are even greater if you think about his disability. When he was 21, Hawking caught a bad illness that slowly stopped him from moving or talking. Now he sits on a wheelchair with a computer by his side. To communicate, he moves two fingers to control the computer's mouse. He chooses his words from the screen, which are then spoken by a voice synthesizer . Hawking also believes that there might be aliens in space. However, he believes they are probably very dangerous, so we should not look for them. "I imagine they might exist in very big ships ... having used up all the resources from their home planet," Hawking said in a British documentary named Into the Universe with Stephen Hawking. The Big Bang theory mainly explains _ . A) how the universe started B) what the universe is like C) how old the universe is D) how the universe exploded
A: A
Q: Have you ever seen any students whose trousers hang so low that you can see their underwear? What do you think of that? Fashionable? Some of today's teenagers are big fans of such a look. But recently this trend has been at the center of an argument in Italian middle schools. The headmaster of a school in central Italy has asked students to stop wearing low-rise jeans that expose underwear and parts of the body. His request came after a class trip, when he saw one boy's baggy trousers slide to his feet. He pointed out that this way of dressing is not suitable for school. But in Italy, a nation that takes fashion very seriously, the suggestion caused a debate among parents, teachers and students. The issue is whether the headmaster's request will limit students' freedom-- or whether dress in Italian schools is too casual. A parents' group praised the move in favor of good taste, while others advised schools to stop worrying about fashion and fix up old school buildings. "We do not want to kick fashion out," the headmaster explained, "but extremes of fashion like this are not right in school." Many other schools have now requested that their students also stop wearing such trousers. Most students have simply ignored the request. Ludovica Gaudio, 14, wore extremely low trousers exposing orange underwear in class. It was cold, so she wore a matching orange scarf. Another 14-year-old said she would probably respect the request, simply for practical reasons. "I don't really feel comfortable in those sort of jeans," said Sarah Lattanzi, "in winter, when dressed like that, it's quite cold and I am afraid my stomach will ache." The argument against the headmaster's request is that _ . A) dress in Italian schools is too casual B) fashion should not be followed in school C) schools should pay attention to things more important than students' clothes D) low-rise jeans can do harm to youngster's health
A: C