Scientists have found living organisms(有机体) that could be 50,000 years old recently. The organisms were found in a hot, but beautiful cave system in Naica, Mexico. These ancient life forms can be seen only with a microscope, which proves they are probably microbes(微生物).

    Penelope Boston leads the Astrobiology Institute at NASA, the space agency of the United States. These ancient organisms are able to exist by eating minerals such as iron and manganese. If the findings are confirmed, they will show how microbes can survive in extreme conditions.

    Researchers have been studying ancient microbes for nine years. Forty different kinds of microbes and some viruses were found in the underground area this time. The genetic(基因的) structures of these organisms are different from those of their nearest relatives –viruses. That is similar to that humans are genetically different from mushrooms growing in forest. The caves in Naica are 800 kilometers deep. Before the miners began working in the caves, the area was isolated from the surface and the outside world.

    Some of the caves are as big as the large religious centers built during Europe's Middle Ages. There are crystals(晶体) covering the walls. Scientists must wear special clothing to keep cool. And the clothing keeps the crystals safe from human germs or other damage. The researchers could only work for about 20 minutes at a time before they have to go to a room that is 28 degrees Celsius to cool down.

    NASA officials would not let Boston share her findings with scientific experts until the last week's announcement. So scientists could not say much about the findings. But Norine Noonan, a biologist at the University of South Florida, said she believed them. “Why are we surprised?” Noonan asked, “As a biologist, I would say life on Earth is extremely tough and versatile.” “What's more, these organisms are not the oldest life forms on Earth. Scientists published studies about living microbes that may be 500,000 years old several years ago,” she added.

    Now many young people are traveling around the world on their own, not because they have no one to travel with, but because they prefer to go alone.

    Kristina Wegscheider from California first traveled alone when she was at college and believes that it is something everyone should do at least once in their life. “It opens up your mind to new things and pushes you out of your comfort zone.” Wegscheider has visited 46 countries covering all seven continents.

    In foreign countries, with no one to help you read a map, look after you if you get ill, or lend you money if your wallet is stolen, it is challenging. This is what drives young people to travel alone. It is seen as character building and a chance to prove that they can make it on their own.

    Chris Richardson decided to leave his sales job in Australia to go traveling last year. He set up a website, The Aussie Nomad, to document his adventures. He says he wished he had traveled alone earlier. “The people you meet, the places you visit, or the things you do, everything is up to you and it forces you to grow as a person,” said the 30-year-old man.

    Richardson describes traveling alone like “a shot in the arm”, which “makes you a more confident person that is ready to deal with anything”. He said, “The feeling of having overcome something on my own is a major part of what drives me each day when I'm dealing with a difficult task. I walk around with my head up because I know deep down inside that nothing is impossible if you try.”

    The great 19^thcentury explorer John Muir once said, “Only by going alone in silence can one truly get into the heart of the wilderness.”

    Three boys were enjoying themselves in their hometown of Bovina, Mississippi .However, their lives were turned upside down when they discovered the jawbone of a Mastodon (齿乳象).

    Brothers Shawn and Caid Sellers and cousin Michael Mahalitc found the prehistoric bone in a piece of earth that was recently plowed (犁、耕)."I thought it was a log," Caid said. "I tried to pick it up and it was really heavy and I saw teeth on it." The bone weighed about 50 pounds. They eventually got the bone to their home and fitted it in their tub (浴盆), but it took their collective strength, might and a golf cart, to carry the large Mastodon bone.

    "They didn't expect to find that," Michael's mom said. "Now that they have, I believe that they will be more aware of their surroundings and what they're digging up when they are digging and playing."

    "We've gotten a lot of petrified (石化的) wood and Civil War relics from the area and that's what I thought it was," the brothers' mother said. "This is our first set of teeth we've found. So we thought it was their imagination. We were quite surprised to see that it was not their imagination."

    They were exploring near the brothers' home. Lo and behold (真想不到), they saw what they thought resembled a fossil. It was the curator of paleontology (古生物负责人) of the Mississippi Museum of Natural Science, George Phillips, who first identified the bone as a "very mature individual."

    The Mastodon was a mammal who lived during the prehistoric times. They had long tusks and trunks, like elephants. They were clearly different from their modern-day counterparts, as well as woolly mammoths (猛犸).

    Knowing what to do at checkout and properly preparing for it can turn a potentially heated situation into a quick thank you add goodbye. Below we made a list of five things you should remember at hotel checkout.

    Don't be late to check

    Hotels may add an extremely high price for being just a half hour late. If you know you won't make the cutoff time, it never hurts to call ahead and try to negotiate away a potential charge.

    Don't forget to double cheek the room and safe

    Make sure you don't leave things behind. If you have an early flight or checkout time, pack up as much as you can the night before so that last-minute rush isn't too annoying. Also, be sure to take out anything in the room safe.

    Don't forget to tip the housekeepers

    It's always polite to leave some money for the people keeping your room clean.

    Don't ignore the detailed bill

    You may be in a rush, but give the detailed hill a careful look to see if the hotel charge is different from the rate you initially booked.

    Don't get angry

    Shooting at the assistant manager standing behind the front desk probably won't help.

    When dealing with an unexpected item on the bill. Think about how difficult it can be to deal with annoyed customers. Keep calm and things may be solved better and sooner.

WELCOME AND ARRIVAL INFORMATION

    Welcome to Harvard University Housing and thank you for choosing to live with us. To help you make a smooth transition please read the information below on panning your arrival.

    Pets

    Dogs living with you in your pet-friendly apartment must be vaccinated(接种疫苗) for rabies and licensed with the City of Cambridge every year.

    International Students

    Consider unlocking your phone prior to leaving your home county. This will enable you to use a SIM card from a company such as campus SIMS or US Mobile in your phone after you arrive. Those SIM cards may be available at the Property Management Office.

    Driving

    If you plan on bringing a moving van or truck it will not fit under the overpasses(天桥) on Soldiers Field Road and Memorial Drive. Plan your route in advance to avoid a risky and costly problem.

    Parking arrangements for trucks and vans must be made in advance as well. Visit your property page for information about parking your car.

    Furniture and Lighting

    Most HUH units have no furniture-the unit is empty except for a stove and a refrigerator. You need to bring, buy, or rent a bed, other furniture, and household items. In many HUH units, rooms do not have overhead lights, so you also may need table or floor lamps.

    If you want to stock up on groceries and some household items as soon as you arrive, please find information about "Grocery Shopping" by clicking the drop-down menu.