Inside the pleasingly fragrant café, So All May Eat(SAME) in downtown Denver, the spirit of generosity is instantly noticeable: A donation box stands in place of a cash register. Customers here pay only what they can afford, no questions asked.

    A risky business plan, perhaps, but SAME Café has done one unchangeable thing in the Mile High City for six years: Open only at midday, the restaurant provides poor local people with healthy, delicious lunches six days a week. Those unable to pay for their meals can instead volunteer as waiters and waitresses, and dishwashers, or look after the buildings and equipment for the cafe.

     “It's based on trust, and it's working all right” , says co-owner Brad Birky , who started the café in 2006. With his wife Libby. Previously volunteering at soup kitchens, the Birkys were dissatisfied with the often unhealthy meals they served there.

     “We wanted to offer quality food in a restaurant where everyone felt comfortable ,regardless of their circumstances,” Birky says. SAME's special lunch menu changes daily and most food materials are natural and grown by local farmers.

    The café now averages 65 to 70 customers (and eight volunteers) a day. And the spirit of generosity behind the project appears to be spreading. In early 2007,one volunteer who had cleared snow for his meals during the long winter said goodbye to the Birkys,” He said he was going to New Orleans to help with the hurricane cleanup,” says Birky.

    In the fall of 1985, I was a bright-eyed girl heading off to Howard University to study law, aiming at a legal career and dreaming of sitting on a Supreme Court bench somewhere. Twenty-one years later I am still a bright-eyed dreamer and one with quite a different tale to tell.

    My grandma, an amazing woman, graduated from college at the age of 65. She was the first in our family to reach that goal. But one year after I started college, she developed cancer. I made the choice to withdraw from college to care for her. It meant that school and my personal dream would have to wait.

    Then I got married with another dream: building my family with a combination of adopt and biological children. In 1999, we adopted our first son. To lay eyes on him was fantastic and very emotional. A year later came our second adopted boy. Then followed son No.3. In 2003, I gave birth to another boy.

    You can imagine how busy I became, raising four boys under the age of 8. Our home was a complete zoo--a joyous zoo. Not surprisingly, I never did make it back to college full-time. But I never gave up on the dream either. I had only one choice: to find a way. That meant taking as few as one class each semester.

    The hardest part was feeling guilty about the time I spent away from the boys. They often wanted me to stay home with them. There certainly were times I wanted to quit, but I knew I should set an example for them to follow through the rest of their lives.

    In 2007, I graduated from the University of North Carolina. It took me over 21 years to get my college degree!

    I am not special, just single-minded. It always struck me that when you're looking at a big challenge from the outside it looks huge, but when you're in the midst of it, it just seems normal. Everything you want won't arrive in your life on one day. It's a process. Remember: little steps add up to big dreams.

    Flying devices called drones(无人机) may be one of the most important technologies of the future.

    The number of jobs for people who know how to design, build and control them is increasing. Because of this increase, several U.S. universities have started offering degrees in unmanned aircraft systems, or UAS.

    One of these universities is the University of Washington in Seattle. Ward Handley is seeking a master's degree in UAS at the university. When the drone program first began, he did not think it was a good idea. “Drones can be used to invade privacy(侵犯隐私).” He said. But later, Handley changed his opinion. He said, “I think there are good enough purposes for them.”

    The FAA (the part of the U.S. government that controls air travel and traffic) is creating new rules to control the use of drones, however. A new law requires drone owners to register(登记) their drones. People who do not register their drones could face fines of up to US$20,000.

    The new rules may also present problems for students. One problem is finding a legal place to fly.

    Students at Blue Mountain Community College fly inside the college gym. In Seattle, University of Washington students test their drones in a big room.

    Christopher Lum, a scientist at the University of Washington, helps students explore how drones can safely share the sky with regular aircraft. Lum explained why they test drones inside a building, “We need to register our aircraft and get permission to fly outside. That process can take months.”

    At this time, Kansas State University is the only school with permission to offer unmanned aircraft flight classes to students outside. The FAA selected Kansas State University and 15 other universities to be part of a national research group.

    Lum and some of his students recently moved their research to Australia. Australia has fewer rules limiting drones. A professor at Western Washington University also took his department's drones to Canada for the same reason.

    A black hole is created when a large star burns out. Like our sun, stars are unbelievably hot furnaces(熔炉) that burn their own matter as fuel. When most of the fuel is used up, the star begins to die.

    The death of a star is not a quiet event. First there is a huge explosion. As its outer layer is blasted off into space, the dying star shines as brightly as a billion suns.

    After the explosion, gravity pulls in what's left of the star. As the outside of the star sinks toward the center, the star gets smaller and smaller. The material the star is made of becomes tightly packed together. A star is so solid that a teaspoon of matter from it weighs billion of pounds.

    The more the star shrinks(收缩), the stronger the gravity inside it becomes. Soon the star is very tiny, and the gravity pulling it in is unbelievably strong. In fact, the gravity is so strong that it even pulls light into the star! Since all the light is pulled in, none can go out. The star becomes black when there is no light. Then a black hole is born!

    That's what we know about black holes. What we don't know is this: What happens inside a black hole after the star has been squeezed into a tiny ball? Does it keep getting smaller and smaller forever? Such a possibility is hard to imagine.

    But if the black hole doesn't keep shrinking, what happens to it? Some scientists think black holes are like doorways to another world. They say that as the star disappears from our universe, it goes into another universe. In other words a black hole in our universe could turn into a "white hole" in a different universe. As the black hole swallows(吞噬) light, the white hole shines brightly--somewhere else. But where? A different place, perhaps, or a different time--many years in the past or future.

    Could you travel through a black hole? Right now, no. Nothing we know of could go into a black hole without being crushed(挤压). So far the time being, black hole must remain a mystery.

    Black holes are a mystery--but that hasn't stopped scientists from dreaming about them. One scientist suggested that in the future we might make use of the power of black holes. They would supply all of Earth's energy needs, with plenty to spare. Another scientist wondered if a black hole could some day be used to swallow earthly waste--a sort of huge waste disposal(处理) in the sky!

    All people need to sleep. Sleep is a restorative(恢复健康的) process that promotes proper body functioning and can improve the quality of your life. Not only is the quantity of sleep important, but also the quality of sleep.

    Your bedroom should be shaped to your taste and allow you to sleep in a peaceful environment. One of the biggest mistakes people make in their sleep is to use the bedroom for activities other than sleep. If your bedroom also functions as a command station for your life and work, the possibility of your sleep being poor is rather high. Bedrooms should be designed, decorated and used for sleep only. TVs, computers and other things should not be in your bedroom if possible.

    Establishing regular sleeping and waking times can help improve the quality of your sleep especially for those suffering from sleeplessness. Avoid hot food, caffeine, sugar and alcohol at least 4 to 6 hours before you go to bed. Develop a regular exercise program. Proper exercise and nutrition will help improve sleep patterns. However, avoid exercising 2 hours before bed, since this may stimulate your body and make it more difficult to fall asleep.

    Establish a pre-bedtime rule that will help you focus on sleep. You can try meditation(沉思), reading or deep breathing and relaxation. Your bedtime rule should be yours. Do not worry about it fitting into a specific category. Do what is best for you.

    Things such as room temperature, noise and light levels and even your bed mattress(床垫) can have a lot of effect on the quality of sleep that you experience. Block out distracting noises and lights. You are in your bedroom to sleep and not be distracted by environmental interference(干扰).

    Wong Fuk-wing, a Hong Kong volunteer at an orphanage (孤儿院) in Yushu, was killed in the earthquake when he was trying to save others on April 14, 2010.

    Wong managed to run safely out of the building with some children when the first quake happened at 7:50 am on April 14, but he went back inside to rescue three other children and three teachers inside, although he knew the danger of aftershocks (余震).

    At 10 am, all the children and one of the teachers were saved. However, Wong was buried under the fallen building and died. The other two teachers were still waiting to be rescued.

    46-year-old Wong was a truck driver, who often said he could only give his efforts to charity instead of money, as he did not earn a lot. His tragic (悲剧的) end touched the hearts of many people both in Hong Kong and on the mainland.

    Wong began volunteering in 2002. In 2003, Wong was told by the doctor he got serious illness, which gave him a great blow. However, the illness did not deter the warm-hearted man. When the earthquake struck Wenchuan is Sichuan Province in 2008, Wong rushed to the disaster area of Shifang to offer his help though his family did not want him to go.

    In fact, Qinghai is a place Wong had often visited since 2006. As a volunteer, he gave out medicine and clothing to the orphanage there. No one could expect that Wong would die helping others.

    Hong Kong Chief Secretary Henry Tang Ying-yen said he had “the highest respect” for the hero who gave his life for others. “What he did has shown the Hong Kong spirit.” The citizens of Hong Kong called him “the pride of Hong Kong's people” and people on the mainland have also praised him as “a true hero”.