When I came to Cincinnati as an au pair (家庭打工留学生), a lot of things there were different from what I knew. My host family lived in a huge house I could only describe as a "castle"．In Germany I had lived in a small apartment together with my mom. Soon I found out that the "castle" was actually rather small in our neighborhood.

    Everybody there was very friendly and polite. They greeted you when they were walking by at least 3 feet away from you. They must not have seen a German au pair before, for most people I met asked me all kinds of questions about Germany. I enjoyed answering their various strange questions. I made a lot of friends and I started to hang out with them.

    Of course, there were a number of new things, and it took me the whole year to find them all out. I never got homesick. Perhaps it was because I did not have too many negative experiences and felt loved and welcomed there.

    However, I had undergone some painful experience back in Germany. I was frustrated by the way people would run me over and not even say "Sorry." Taking up my studies at the TU-Dresden, I felt lonely. Everybody here seemed to be withdrawn(离群的) and I missed everything I had in Cincinnati. Germany was so "cold". I found it so much harder to make new friends. After six months I got a roommate and only two good friends. I also flew back to Cincinnati several times for long periods. I felt that without those visits I was not able to make it.

    Now I am over this German culture shock. It almost took me an entire year. I am still going back and forward between Dresden and Cincinnati four times a year.

    For thousands of years, we have looked for ways to measure time. Early humans found that the regular movements of the sun, the earth> the moon, and the stars made good ways to measure time. The rising and setting of the sun were used to distinguish (辨别) day from night.

    But, eventually, people needed to tell time more accurately, or exactly. So, by using the sun's position in the sky, they divided the day into dawn, morning, midday and evening.

    Then it was noted that the sun cast a changing shadow as it moved across the sky. Time could be told more accurately by setting up a stick and marking the positions of the sun's shadow. It was the ancient Greeks who divided each position of this “sundial (日晷)” into hours.

    But the sun doesn't always shine. So, for the past 6,000 years, many other ways of keeping time have been tried. Slow-burning candles were divided into hours, and the hourglass was invented. When all the sand in the top of an hourglass has shifted to the bottom, an hour has passed.

    Later, the pendulum (摆钟), with its regular back-and-forth movement of weights, was used to move the hands on a clock. Pendulums are still used in grandfather clocks.

    Today, even more accurate clocks are in use, such as battery-operated quartz clocks (石英钟), digital clocks, and clocks run by electrical tuning forks and tiny atoms. These atomic clocks are the most accurate clocks ever invented. The exact time can be kept to within 1 second a century.

    Looking almost as fresh as the day it was bought, this McDonald's Happy Meal is in fact six months old. Photographed every day for the past six months by Manhattan artist Sally Davies, the kids meal of fries and burger hasn't any signs of mould(霉菌) or decay(腐烂).

    Sally put the Happy Meal on a shelf in her apartment and watched it with increasing shock. Even her dogs stopped trying to steal a free tasty snack.

    “I bought the meal on April 10 this year and brought home to see how it changed,” she said. “I chose McDonald's because it was nearest to my house, but the project could have been about any other fast food. The first thing that shocked me on the second day of the experiment was that it no longer gave out any smell. And my dogs stopped circling the shelf.”

    Sally expected the food to go mouldy after a few days. In fact, Mrs. Davies' surprise turned to shock as the food still had not shown any signs of decay after two weeks. “It was then that I realized that something strange might be going on with this food that I had bought,” she explained. “The appearance of the food did not change as the weeks turned to months. And now, at six months old, the food is plastic to touch. The only change that I can see is that it has become as hard as a rock.”

    The experiment has brought her amusement rather than fear. “Maybe I would be frightened at seeing this if I were a meat eater.” she said.

    A recent university study found that current electric cars could be used for 87% of daily car journeys in the US. That figure could rise to 98% by 2020.

One hurdle to the widespread adoption of electric cars has been “range anxiety” —drivers' concerns about running out of petrol on a journey. While petrol stations are conveniently located across national road systems, the necessary network of electric charging stations is still being developed. In fact, charging points are becoming increasingly common throughout the USA.

    Attitudes towards electric vehicles have changed quite considerably over the last few years. Not that long ago, electric cars met with doubt, and their high price drove customers away. Thanks to improvements in battery capacity(电池容量), recharging times, performance and price, the current generation of electric cars is starting to persuade critics.

    As well as progress on the road, electric vehicles are taking to the sea and sky. Electric boats are among the oldest electric vehicles, having enjoyed several decades of popularity from the late 19th to the early 20th century before petrol-powered outboard motors took over. Now, the global drive for renewable energy sources is bringing electric boats back. Steps towards electric planes are also being made, with Airbus and NASA among the organizations developing and testing battery-powered planes. The experiments could soon make electric flight a reality.

    Electric vehicles do not produce any emissions(排放物). Were the US to act on the study's findings and replace 87 percent of its cars with electric vehicles, it would reduce the national demand for petrol by 61 per cent. However, because of the production processes and the generation of electricity required to charge these vehicles, they cannot claim to be completely emission-free. Even so, as many countries continue to increase their use of renewable energy sources, electric vehicles will become even cleaner.

    We often ask these questions: Are African wild dogs really dogs? What's the difference between African wild dogs and the dogs we know as pets? For one thing, African wild dogs, which live in Africa, only have four toes, while domestic(驯养的）dogs and wolves have five. But you won't want to count for yourself, because they are truly wild animals.

    “Wild dogs are not somebody's domestic dogs that ran away and didn't come back, although some people used to think that,” explains Dr. MeNutt, who studies these animals at Wild Dog Research Camp in the African country of Botswana. “They are actually Africa's wolves, and just like wolves, and they do not make good pets. They need to be out in the wild doing what they are supposed to do — find the food they need to survive and feed their babies.” In fact, they travel so far that researchers have to use radio collars (颈圈) to keep track of them. The collars send out radio signals that tell people where the dogs are. No two wild dogs have the same pattern of coats, so it is easy to tell them apart.

    African wild dogs are smart and sociable, like pet dogs. Adult wild dogs, male and female, are willing to take good care of young ones.

    Millions of domestic dogs live on the planet, but there are probably fewer than 6000 African wild dogs left. Humans hunt them and farmers who don，t want them to go after cows and sheep poison them. Humans are also destroying the wild, natural habitat (栖息地) they need to survive in. Fortunately, today more farmers are finding other ways to protect their cows and sheep from African wild dogs instead of killing the animals.

    Have you ever heard of agritourism where you can experience farm life? If not, Dr. Cindy Ayers-Elliott will tell you the real story of Foot Print Farms.

    The original concept of building Foot Print Farms was simple. When Ayers-Elliott returned to her hometown after graduation, she didn't have to look any further than her state's alarming health statistics to find a mission. Everywhere she turned, there were reports of high blood pressure, diabetes, obesity and heart disease. "The problem was already identified." explains Ayers-Elliott. "Too many Mississippians were seriously unhealthy and it didn't take research to see that. And many of the state's greatest health challenges could directly result from poor diet. "

    These days, Foot Print Farms, which started with a few raised beds of herbs and vegetables, is making fresh, naturally grown food. "When speaking of the key to my success, the co-op model works because we share the work and rewards," notes Ayers-Elliott. "A perfect example is the Wingfield High School football team. To earn the money for equipment and other items, players committed to working five hours a week on the farm, and by the end of the summer they had produced 1, 000 melons and the profits from their sales helped to buy weights, T-shirts, sweat suits and pregame meals. But the lessons they learned about the rewards of hard work and working together to accomplish something were even more valuable products of their efforts."

    "It' s a model that can easily be learned in other places and I' m looking forward to seeing some of our current partners do just that——to take what they have learned here and spin it off in other communities," Ayers-Elliott remarks. She is now looking forward to developing an agritourism aspect to the farm, where visitors can experience farm life, learn new skills and take with them seeds of inspiration they can sow in their own communities when they return home.