Winters are long and unforgiving in North Dakota. The winter of 1996 was especially brutal. It was a hard time in my own life too. A neck injury had kept me flat in bed for nearly a year. “Just in time for Easter,”my husband, Dick, said. But how could I feel the joy when the snow was four feet deep and I had months of painful physical treatment ahead?

    I was doing the dishes one day, feeling hopeless when there was a tap against the glass. It was a branch of the troublesome cottonwood (棉白杨).Back in the fall of 1979, it was a new subdivision (分支）then, an eight-foot stick. The people who'd briefly occupied the house before us had placed the pipe from the pump next to it. The earth was so wet that the poor thing had fallen down, most of its bare root system pointing skyward, and blowing hopelessly back and forth in the cold wind. Dick decided to pull it out one day, but I protested.

    “Look at how hard it's trying!” I said, pointing to the way it strongly kept hold of the earth. “It deserves a chance.”

     Dick borrowed some tools. We packed dry soil around the tree and put up some stakes (桩) into the ground, making it stand upright. That winter was still terrible. Surprisingly,in the spring my “rescue stick”put forth a few leaves,then with lots of branches. The year after that, we were able to remove the stakes. By the 1990s that little stick was a giant, towering over the house.

    Now the tapping at the window continued, louder as the wind picked up, almost as though to tell me to look up. At last, I did. I caught my breath. In the window against the icy blue sky, thousands and thousands of fresh red buds were waving in the wind.

    The tree was bursting with life and I had a wonderful Easter.

    As soon as a person dies, decomposition(分解) begins. And the first visitors arrive. “Within 5 to 15 minutes of death, flies or other insects begin to colonize the body.” says Rabi Musah, an organic chemist at the University at Albany.

    She says different species turn up at different stages of decomposition. “So because of that, depending upon what entomological(昆虫学的) evidence you find, you can learn something about when the person died in terms of the timing of the death.”

    Flies don't tend to stick around when disturbed by detectives. But they do leave behind eggs. The eggs are hard to tell apart by appearance alone, so specialists raise them until they hatch, a few weeks later—and they get a species ID and, with a little guesswork, a person's time of death.   But Musah has come up with a more time-saving approach: chemical analysis of the eggs. She and her team investigated that method by first harvesting flies with pig-liver traps hidden throughout New York City. They collected the trapped flies and then chemically analyzed their eggs. And it turns out each species of fly egg has a unique chemical fingerprint—enough to tell the eggs apart without raising the eggs to maturity. The study is in the journal Analytical Chemistry.

    Musah and her colleague Jennifer Rosati are now testing the method on a real case. “And once we do that we will be publishing some case studies to illustrate(阐明) that this is a method that can be used, and hopefully eventually it's something that will stand up in court, and something that could speed up detective work—or help deal with a cold case.”

    On Saturday evening, CCTV showed a computer-generated image of the Chang'e 3 lander's path as it approached the surface of the moon, saying that during the landing period it needed to have no contact with Earth. As it was just hundreds of meters away the lander's camera broadcast images of the moon's surface.

    The Chang'e 3's solar panels, which are used to absorb sunlight to generate power, opened soon after the landing. The mission blasted off (发射) from southwest China on Dec. 2 on a Long March-3B carrier rocket. It is named after a mythical Chinese goddess of the moon and the “Yutu” rover vehicle, or “Jade Rabbit” in English, afternoon the goddess' pet.

    China's military-backed space program has made much progress in a relatively short time, although it is behind the United States and Russia in technology and experience. China sent its first astronaut into space in 2003, becoming the third nation after Russia and the United States to achieve manned space travel independently. In 2006, it sent its first probe (探测器) to the moon. China plans to open a space station around 2020 and send an astronaut to the moon after that.

    “They are taking their time with getting to know about how to fly humans into space, how to build space stations, how to explore the solar system, especially the moon and Mars. They are making big advancements, and I think over the next 10-20 years they'll certainly be matching Russia and America in this area and maybe overtaking them in some areas.”

    A food chain is a simple way of explaining how each living thing gets its food. For example, a simple African food chain might consist of three parts: first, trees and bushes; second, giraffes; and third, lions. Each link in a food chain is food for the next link. Food chains always start with plants and end with animals.

    Plants are at the bottom of the food chain. Scientists call them producers, because they use light energy from the sun to produce food from carbon dioxide and water through photosynthesis（光合作用）. Animals, unlike plants, can't produce their own food. Instead, they must eat plants or other animals. This is why scientists call them consumers.

    Consumer animals fall into three categories. Herbivores（食草动物）eat only plants. Carnivores（食肉动物） eat only other animals. Omnivores eat both plants and animals. In addition to producers and consumers, there are also decomposers(分解者).These organisms, such as bacteria and fungi, feed on decaying(腐烂) matter. They help the food chain by speeding up the decaying process that releases minerals back into the soil to be absorbed by plants as nutrients.

    Most food chains have only four or five links in them. As you go up a food chain, the amount of energy at each level diminishes, because some of the energy is lost in the form of waste or is used up by the organism at the level. That is why it takes many plants, for example, to feed a few giraffes who in turn feed one lion.

    Most animals are part of many different food chains, because they must eat more than one type of food to satisfy their energy needs. All of these interconnected food chains form a more complex structure called a food web. Humans, for example, are at the center of a very complex food web, because we tend to eat many different types of plants and animals.

    When hospital staff are in full scrubs (手术衣), their faces are almost completely covered by their caps and face masks, and we can only see their eyes and eyebrows. In order to solve the problem, a doctor in Sydney, Australia, called Rob Hackett launched a campaign named "Theatre (手术室) Cap Challenge"-encourage hospital staffs to write their' names and roles on their caps. At first, his colleagues didn't take it seriously. However, with time going on, it has been adopted around the world with studies from the US and UK reporting how this simple idea can decrease human errors in healthcare.

    "I went to a theatre where there were about 20 doctors and nurses in the room," Dr. Rob Hackett said. "I struggled to even ask to be passed some gloves because the person I was pointing to thought I was pointing to the person behind them, because I don't know their names." said Rob. As we all know, doctors are a stressful profession. When faced with life and death, they need to save the patient's life for a second. At the moment, effective communications are important.

    "The 'Theatre Cap Challenge' is in response to concerns about how easily avoidable mistakes and poor communication are contributing to rising harmful events for our patients." said Rob. "We need to develop systems which reduce mistakes and misunderstanding without causing harm. For this to happen, we need to let everyone know we're human." he added On the other hand, from the patients' viewpoint, caps with names on them can make patients more unworried. When everyone appears the same, it is extremely difficult to distinguish who is who. Knowing them relaxed.

    In 1972, a social worker named Sanjit Bunker Roy founded Barefoot College in Tilonia, Rajasthan. Today the college trains women from villages for six months to build and maintain solar panels and other instruments. Barefoot College also offers education to the younger generation both during the day and at its solar bridge schools that meet by lamplight at night.

    The philosophy of Barefoot College is largely inspired by the principles of Gandhi, starting with equality beyond caste (种姓), gender or religion. As a matter of fact, women are prioritized (优先考虑) as an underserved population that is essential to bringing villages together. Another central principle of the college is self-reliance, teaching students to support and think for themselves.

    After the college's female students have completed their half-year of training, they return to their villages where they wait for solar panel parts to arrive from the college. Once they have all the pieces they need, they construct the panels and begin collecting solar energy. For each village, the college also provides solar lamps. Villagers can, in addition, order parts for other solar-powered devices, such as water heaters and cooking stoves. Once assembled, they and the lamps are powered by the solar panels.

    The effect on the villages is huge. Before the solar panels and lamps arrived  villagers had only candles to light their homes. This prevented adults from doing serious work at night, and it made studying difficult for children as well. As for physicians, they had difficulty treating patients and performing operations at night because they had to rely on flashlights.

    Now there is power for not only the electrical appliances that the college provides but also devices like televisions, radios and computers. For the first time, the villagers can even connect to the world through the Internet.