Question: I'm taking a test and have to guess the right answer to the question after the article. Article: Using tablet computers like Apple's iPad and Samsung's Galaxy Note just before bed can lead to a poor night's sleep, according to research. More and more people are taking their tablets to bed with them to surf the web, check Facebook or email before switching off the light. But researchers are warning that the blueish light their screens emit can stop users getting a good night's sleep. That is because this type of light mimics daylight, convincing the brain that it is still daytime. Blue light suppresses production of a brain chemical called melatonin, which helps us fall sleep. This is because our brains have evolved to be wakeful during daylight hours. By contrast, light which is more orange or red in tone does not reduce melatonin production, perhaps because our brains recognize it as a cue that the day is ending. Neurologists have known for years that staring at screens late in the evening can disrupt sleep. Researchers at the Lighting Research Centre, at the Rensselaer Polytechnic Institute in New York, are warning that looking at tablet displays for more than two hours "leads to a suppression of our natural melatonin levels as the devices emit optical radiation at short wavelengths" - in other words, they emit bluer light. They say: "Although turning off devices at night is the ultimate solution, it is recommended that if these devices are used at night displays are dimmed as much as possible and that the time spent on them before bed should be limited." They drew their conclusions after measuring melatonin levels in 13 volunteers, after they had spent time viewing iPads at full brightness at a distance of 10 inches, for two hours. Melatonin levels were significantly lower after they had done this, than they were after the volunteers had viewed their iPads for the same time, but while wearing orange glass goggles, which cut out the blue light. They wrote in the journal Applied Ergonomics that tablet makers could "tune the spectral power distribution of self-luminous devices " so that they... Question: We can infer from the passage that _ . Options: A: Orange and red light does no good to a good night's sleep. B: Our brains recognize orange or red light in tone as a cue that the day is ending. C: The less melatonin our body produces, the easier we fall asleep. D: Too much late night screen time leads to more than sleep problem.
Answer: D

Question: I'm taking a test and have to guess the right answer to the question after the article. Article: The Underground Railroad wasn't underground and it wasn't a railroad. But it was real just the same. And it was one of the brightest chapters in American history. The Underground Railroad was a secret network of people who helped slaves flee to freedom before the Civil War. The slaves were black people from families who had been brought from Africa in chains. They were owned by their white masters and forced to work without pay. The first slaves arrived inprefix = st1 /Jamestown,Virginiain 1619. Two hundred years later, there were nearly four million slaves in theUnited States. Most worked in large plantations in the South. By then, slavery had been outlawed in most northern states. Many slaves were treated cruelly. Some were not. All could be bought and sold. Some slaves bought their own freedom by earning money during time off from work at the plantation. There were free black people in both the North and South during slavery days. Thousands of slaves ran away each year. Some fled to get away from harsh masters. Others wanted to enjoy liberty. The Underground Railroad was started to help them. The "station" of the Underground Railroad were homes, shops, and churches where runaway slaves were hidden and fed. The "agents" or "stationmasters" were people --- both black and white --- who hated slavery. They wanted to help slaves get free. "Conductors" on the Underground Railroad led or transported fugitives from station to station on their way to free states. They had to watch for slave catchers, who were paid to capture runaways and return them. Some conductors guided slaves all the way to Canada. The most famous conductor was Harriet Tubman. She was a strong, determined woman. Before she became a conductor, Mrs. Tubman had been a passenger on a dangerous journey on the Underground Railroad. She lived as a slave on the plantation inMaryland. One day in 1849, Mrs. Tubman heard that she was going to be sold. She decided to escape instead. Harriet... Question: What the Underground Railroad didn't have was _ . Options: A: "stations, conductors and agents" B: people who hated slavery C: slave catchers D: slave owners
Answer: D

Question: I'm taking a test and have to guess the right answer to the question after the article. Article: 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. Question: What does the passage mainly tell us? Options: A: The causes of road accidents. B: The advantages of fly ash. C: The measures of avoiding road accidents. D: Latest information about long-life concrete bridges.
Answer:
D