The failed Skylab will come screaming home to the earth in disappointment sometime next month, but we don't know where it will fall. That precise information is beyond even the calculations of scientist and their computers. The best they can tell us is that the space station, weighting 77 tons and as high as a 12-story building, will break into hundreds of pieces that will be scattered across a track 100 miles wide and 4,000miles long. We are again exposed to one of those unexpected adventures, or misadventures, of science that attract our attention from the boring routines of daily existence and encourages us to think a lot about man's future. What worries Richard Smith, the Skylab's director, is the "big pieces" that will come through the atmosphere. Two lumps, weighing 2 tons each, and ten, weighing at least 1,000 pounds each, will come in at a speed of hundred of miles an hour, and if they crash on land they will dig holes up to 100 feet deep. What worries us, with our lack of scientific knowledge and our quick imagination, is both the big and little pieces, although project officials say there is a very small chance that anyone will be injured by them. That's good to know, but it doesn't remove the doubt of the millions who still remember the nuclear accident at Three Mile Island. That accident took place in 1979 in spite of what scientists had assured(...) us as to the safety of the nuclear reactor . The writer mentions Three Mile Island _ . A) because he fears that a piece of the Skylab may strike a nuclear power plant B) to express his doubt about the officials' words C) because he is afraid of nuclear power D) because the nuclear reactor there and the Skylab were built by the same company
B
(Question)
Whether it's for a hobby or profession, photography has always been highly valued. Photography has been around for over a hundred years, but what has recently revolutionized it is digital photography. A digital camera looks like a film camera, but it works differently. A digital camera takes pictures or a video by using a CCD sensor instead of film. The data about the images are electronically saved on a flash card. Later on, the flash card can be removed from the camera and put into a card reader. The card reader can be plugged into a computer's USB port. The images and videos can then be saved on a computer for viewing, editing, emailing, or printing. Digital photography received a great deal of criticism in its beginning stages, but with its continued development, it is now capable of producing images of a quality that is similar to. or even better, than that of film photographs. However, what really makes digital photography attractive is its convenience and low cost. Instead of having to go to a lab and waiting to get pictures developed to see what they look like, you can always view the images or-video on the LCD screen that is on the back of the camera. Not only does this feature save time, but it also prevents common mistakes like using a wrong exposure( ) that could ruin an image or video. With the usage of computer programs like Photoshop, more serious photographers can edit their images without the expense of a darkroom. Digital photography is also friendlier to the environment, as harmful chemicals that are needed in the development of film are not used in digital photography. Printing only the best pictures and not having to buy film make digital photography much cheaper. Which is NOT a reason why digital photography is eco-friendly? A) Harmful chemicals are not needed in developing pictures. B) Pictures are printed with a computer instead of films. C) Photographers don't have to work in a darkroom. D) Digital cameras produce pictures as good as film cameras.
(Answer)
D
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... Twenty-four still photographs are made into a continuous moving picture just because _ . A) the image we see usually stays longer than it actually appears. B) we see an object in comparison with its surroundings. C) the eyes catch million pieces of information continuously. D) rods and cones send messages 20 to 25 times a second.
Ans: A
Mother's Day is coming up. Maybe your gift is wrapped and your dinner plans booked for mom, step-mom, grandmother - whoever the person is who fed, cared for, taught and loved you. But there are other people who said their most special Mother's Day memories rarely dealt with beautifully wrapped objects, but rather, the ways people showed they cared. Mother's Day 2012 was the last one Jannet Walsh was able to celebrate with her mother, Margaret, who had a stroke in 2009. In her last few years, Walsh always shot photos and videos of their visits together, and with Walsh's West Highland White Terrier, Andrew. "My mother had a dog just like him, so I would tell her it was her dog, and she would hold onto his leash, even in bed up to the last few weeks before she passed away," Walsh said. As Mother's Day approached, Walsh wanted a way to remember her mother and "best friend". She decided to build the memories she captured during those last few years into a video memorial - images of her mother with Andrew or quiet moments at her gravesite. "I thought it good to tell the story with few words, just show my mother as she was - happy, and loved till the end," Walsh said. Mother's Day was not a light-hearted subject for Wendy Bowers in the past. Her mom had walked out when she was 18, and Bowers had tried for years to become pregnant without success. She had almost convinced herself she wasn't meant to be a parent. But three years after she gave up on having a baby, Bowers discovered that she was pregnant. Six weeks earlier than expected, little Nathan arrived. That first year, Nathan, only 10 months old, was sick with a stomach bug. Bowers said she spent the day holding him between loads of laundry. "I would not have been anywhere else in the world that day," she said. "I wouldn't trade that first Mother's Day for anything, and I'm pretty sure Mother's Day will always be a reminder to me of just how lucky I am to even be a mom." How does Bowers feel about what happened on her first Mother's Day as a mother? A) It was worth it. B) It was unlucky. C) It was unexpected. D) It was unbearable.
A