Gray hair is simply a part of the normal aging process, and the rate you go silver is genetically predetermined. Going gray is not associated with earlier death, and premature graying is not, generally speaking, a sign of an illness or ill health in younger adults. There are, however, some specific health conditions associated with gray or white hair, but for most of us, going gray is just a fact of life. Hair color1 comes from the pigment melanin , which determines your individual shade. Hair without any melanin is pure white. The pigment is produced in cells called melanocytes, which inject pigment into the hair. At some point in everyone's lifetime, these cells slow down and eventually stop producing color1. Scientists have yet to identify the exact mechanism by which melanocyte cell death occurs. A study of more than 4,000 women and men from 20 countries determined that about 75% of people between the ages of 45 and 65 have some gray hair. In general, people of European descent gray earliest followed by Asians and Africans. It's interesting to note that a lucky 1 in 10 has no gray hair by retirement age. Beginning at age 30, your chances of having gray hair go up 10-20% per decade. It may feel like you have more grays after a stressful event, but that's probably because middle age is basically a series of anxiety-ridden events. Between working, raising kids, and caring for older parents, the "sandwich" years of 45-65 can be stressful, especially for women. They are also when we naturally start to look older. At this point, there is still no silver bullet to keep away the grays. Which is not among the reasons for hair turning gray according to the passage? A) Being physically weak. B) Stress from different sides. C) Death of melanocyte cell. D) Genetic factors.
A
Excused from recycling because you live in a high rise with a rubbish chute ? You won't be for long. Miami's Mark Shantzis has made it simple for those living in tall buildings to use the chute and recycle too . In Shantzis' Hi-Rise Recycling System, a chute leads to a pie-shaped container with six boxes that can turn around when operated. The system , which fits in the same space as the chute and container now in use, enables glass , plastic , paper , metal , and other rubbish to go into separate boxes . The system is controlled from a board next to the chute door. The board has a button for each class of recycling materials (as well as for unrecyclables). At the press of a button, a microcomputer locks all other floors' chute door and sets the recycling container turning until the right box comes under the chute. The computer also counts the loads and gives a signal by phone when the box is full. And a particular piece of equipment breaks up the nonrecyclables Sorting recyclables before they are collected saves the use of expensive materials recovery equipment which otherwise has to do the sorting . Such equipment often makes recycled materials very expensive, so expensive that tons of recyclables remain wasted . Shantzis believes his system could help recycled materials become more cost-effective. The purpose in writing this text is _ . A) to encourage people to recycle their rubbish B) to introduce a recycling system for high rises C) to describe the use of computer technology in recycling D) to explain the need for rubbish collection in high rises
B
Q: As the new term starts, freshmen around the world are asking the same question: how can I make the best of four years at college? The New York Times received suggestions recently from PhD students and seniors at some of the top universities . Here is their advice. "Many young people today are raised in a protective cocoon ", wrote Tim Novikoff, a PhD student at Comell. "College is a time to explore the world beyond and a chance to learn new things about yourself. Take classes in different subjects. Try lots of different clubs and activities." Remember also to take some time away from campus, suggested Willie Lin, a student at Washington University. " _ " Try to find work assisting a researcher or a professor---this is the advice from Aman Singh Gill, a PhD student at Stony Brook University. And he also said, "With a window into the world of research, you will find yourself thinking more critically, accepting fewer states at face value and perhaps developing a brave sense of what you can accomplish." Many young people can't imagine even a single day without devices such as computers and cell phones. But try to keep yourself off them, cautioned Christine Smallwood, a PhD student at Columbia University. Start by scheduling a few Internet-free hours each day, with your phone turned off. It's the only way you'll be able to read anything serious. "This will also have the benefit of making you harder to reach, and thus more mysterious and fascinating to new friends and acquaintances ," she suggested. This passage is mainly about _ . A) tips from some students for college life B) ways to read something serious regularly C) days without cell-phones and computers D) chances to go to university you really like
A: A
Question: On Jan 23, 2012, I was aboard a ship on the Yangtze River, listening to the sound of fireworks and eating plate after plate of dumplings. On Sunday Feb 10, 2013, I was preparing to celebrate Chinese New Year again - in London's Chinatown. It was raining. It was cold. But ever since I left Beijing in August, I had promised myself I would celebrate Chinese New Year - if only to help with my Beijing "homesickness". Central London was dressed up for the occasion. There was a stage for a big fireworks display for the evening. Even so, it wasn't like my real Beijing chunjie. Even buying a baozi didn't cheer me up. It cost about 10 times as much as the real thing does in Beijing and got stuck to its rain-ruined paper bag. Cold, wet and depressed, I ran into a shop for shelter. Suddenly, there it was. Between the packets of dried meat and fish, the bags of rice and the smell of dried noodles in this little Chinese supermarket, I had found home. An hour later, I hurried into my house with bags of frozen jiaozi, packets of sauce and a large bottle of vinegar. I boiled water, tore open the packets, grabbed my chopsticks and settled down to a feast. This, I thought, is a Happy Chinese New Year. I even watched the fireworks on TV. After all, why face the British weather when I can bring China home in one bite? How did the author feel when she found some Chinese foods in a supermarket? A) a little curious B) rather tired C) a bit comfortable D) very depressed
Answer: C
After a particularly busy period at work, I decided to get away from it all by going on a hike in the mountains in southern France. Before I left, I read an interesting story in a magazine. It read, "Once, while I was riding on a crowded bus, the man sitting next to me threw his cell phone out of the window when his phone rang. I was surprised. He looked at me, shrugged and looked away. I had no idea whether it was his or stolen or whether he even knew what a cell phone was or not, but he clearly wanted to be free of it, because it clearly troubled him. " Billions of people across the world use cell phones. Though cell phones are a wonderful way for communication, they often do the exact opposite. Using cell phones can increase stress within families and friends. So when I recently returned home, I got rid of my cell phone. Now I go outside without taking my phone with me. I've noticed things in my neighborhood I never noticed before, such as gardens. I've met new people, started conversations with neighbors I didn't speak to before and talked with some of my friends face to face instead of chatting over the phone. Instead of keeping me off from the world, stopping using my cell phone has helped me get even closer to my family and friends. The main purpose of the passage is to _ . A) tell us not to let cell phones control our lives B) encourage others to hike with him in France C) share his experiences in France with us D) teach us how to get along with neighbors
A