Ques: You stare at waterfall for a minute or two, and then shift your gaze to its surroundings. What you now see appears to drift upward. These optical illusions occur because the brain is constantly matching its model of reality to signals from the body's sensors and interpreting what must be happening--that your brain must have moved, not the other; that downward motions is now normal, so a change from it must now be perceived as upward motion. The sensors that make this magic are of two kinds. Each eye contains about 120 million rods , which provide somewhat blurry black and white vision. These are the windows of night vision; once adapted to the dark, they can detect a candle burning ten miles away. Color vision in each eye comes from six to seven million structures called cones . Under ideal conditions, every cone can "see" the entire rainbow spectrum of visible color1s, but one type of cone is most sensitive to red, another to green, a third to blue. Rods and cones send their messages pulsing an average 20 to 25 times per second along the optic nerve. We see an image for a fraction of a second longer than it actually appears. In movies, reels of still photographs are projected onto screens at 24 frames per second, tricking our eyes into seeing a continuous moving picture. Like apparent motion, color1 vision is also subject to unusual effects. When day gives way to night, twilight brings what the poet T.S. Eliot called "the violet hour." A light levels fall, the rods become progressively less responsive. Rods are most sensitive to the shorter wavelengths of blue and green, and they impart a strange vividness to the garden's blue flowers. However, look at a white shirt during the reddish light of sunset, and you'll still see it in its "true" color1--white, not red. Our eyes are constantly comparing an object against its surroundings. They therefore observe the effect of a shift in the color1 of illuminating on both, and adjust accordingly. The eyes can distinguish several million graduations of light and shade... The visual sensor that is capable of distinguishing shades of color1 is called   _  . A) cones B) color1 vision C) rods D) spectrum
Ans: A

Ques: *What prevents depression:tea,coffee or hot chocolate? Women who drink for or more cups of coffee a day are a fifth less likely to become depressed.Drinking two or three cups reduces the risk by 15 percent. This is the result of a study of 51,000 women over ten years, published in the Journal of the American Medicine Association. One theory is that caffeine reduces the  effect of the chemical adenosine  in the brain, which can make us feel sleepy by slowing down nerve cell activity. Some anti-depressants also work by blocking the adenosine receptors. Coffee was found to be far more influential on depression levels than hot chocolate or tea due to the high caffeine content. *How many eggs can we healthily eat: one a day or two a day? Neither-eat them freely. We've long been warned to stick to two or three eggs a week because of their high cholesterol content. But according to the Food Standards Agency, there is no recommended limit to how many eggs we can healthily eat, unless you have been told to cut down by your doctor. There is no evidence that eating eggs raises cholesterol levels, and researchers found that eggs contain less cholesterol than in the past because hens are no longer given bone meal, which was banned in the 1990s after the BSE  cresis. Research by the British Egg Council found that a medium egg gives you around 100 mg of cholesterol, a third of the 300mg recommended daily limit. What is considered to fight depression best? A) Tea. B) Chocolate. C) Adenosine. D) Coffee.
Ans: D

Ques: Americans think that travel is good for you. Some even think it can help to solve one of the country ' s worst problems ~: crime  . Crime worries a lot of people. Every year, the number of crimes is up and up. And many criminals  are young. They often come from sad homes, with only one parent or no parents at all. There are many young criminals in prison,but prison doesn ' t change them. Six or seven in ten will go back to crime when they come out of prison. One man ,Bob Burton, thought of a new idea. In the old days, young men had to live a difficult life on the road. They learned to be strong and brave, and to help their friends to be strong and brave, and to help their friends in time of danger. This helped them grow into men. So Bob Burton started "Vision Quest. " He takes young criminals on a long ,long journey with horses and wagons  , 3,000 miles through seven states. They are on the road for more than a year. The young people in Vision Quest all have bad problems. Most of them have already spent time in prison. This is their last chance. It's hard work on the road. The day starts before the sun comes up. The boys and girls have to feed the horses. Some of them have never loved anyone before  but they love their horses. That love can help them to live a new life. Not all the young people on Vision Quest will leave crime behind them. Three or four in ten will one day be in prison again. Bob Burton is right. Travel can be good for you. Even today, Americans still say, " Go west, young men. " Americans still say, "Go west, young men. "because . A) if they go west they can have a travel B) in the west there is a prison C) there they have to live a hard life to grow into men D) prison doesn't change them
Ans: C

Ques: Among the more colorful characters of Leadville's golden age were H. A. W. Tabor and his wife, Elizabeth McCourt, better known as "Baby Doe". Their history is fast becoming one of the legends of the Old West. Horace Austin Warner Tabor was a school teacher in Vermont. Then he moved west to the small Colorado mining camp known as California Gulch, which he later renamed Leadville when he became its leading citizen. "Great deposits of lead are sure to be found here." he said. As it turned out, it was silver, not lead, that was to make Leadville's fortune and wealth. Tabor knew little about mining himself, so he opened a general store, which sold everything from boots to salt, flour, and tobacco. It was his custom to " _ " prospective miners, in other words, to supply them with food and supplies, or "grub", while they looked for ore , in return for which he would get a share in the mine if one was discovered. He did this for a number of years, but no one that he aided ever found anything of value. Finally one day in the year 1878, so the story goes, two miners came in and asked for "grub". Tabor had decided to quit supplying it because he had lost too much money that way. These were persistent, however, and Tabor was too busy to argue with them. "Oh help yourself. One more time won't make any difference," He said and went on selling shoes and hats to other customers. The two miners took $17 worth of supplies, in return for which they gave Tabor a one-third interest in their findings. They picked a barren place on the mountain side and began to dig. After nine days they struck a rich vein of silver. Tabor bought the shares of the other two men, and so the mine belonged to him alone. This mine, known as the "Pittsburgh Mine," made $1,300,000 for Tabor in return for his $17 investment. Later Tabor bought the Matchless Mine on another barren hillside just outside the town for $117,000. This turned out to be even more fabulous than the Pittsburgh, yielding $35,000 worth of silver per day at one time. Leadville grew.... Leadville got its name for the following reasons EXCEPT that A) Tabor became its leading citizen. B) great deposits of lead is expected to be found there. C) it could bring good fortune to Tabor D) it was renamed
Ans:
C