Sometimes, you just can't help it. Maybe you're watching a sad movie, or thinking about the friend who moved away. Next thing you know, your eyes are watering, and you havetears running down your cheeks. Why do peoplecry when they are emotional? What are tears? Scientists are working hard to find the answers to these questions.

    Ad Vingerhoets is a professor of psychology at Tilburg University, in the Netherlands. He is one ofthe few scientists in the world who have studied crying. According to Vingerhoets, there are three types of tears. Basal tearsare the first type. Theylubricate(润滑) the eyes andact as a protective barrier between the eye and the rest of the World. Next arereflex tears. They wash youreyes clean when something gets in them. Finally, there are emotional tears. “These are released in response to emotional states, ”explains Vingerhoets. “Especially when we feel helpless.”

    Scientists believe that crying has something to do with how humans developed and learned to depend on each other.“Humans are very complex social creatures,”says Lauren Bylsma, a professor at the University of Pittsburgh, in Pennsylvania.“It seems that tears serve to arouse help and support from others," She says. “Another reason we weep is that humans have the longest developmental period of almost any animal. It takes along time to grow up. ”

    Vingerhoets agrees. “I think that the reason why humans shed tears(流眼泪) has somethingto do with our childhood,”he says. “That's the time when we are stir dependent on adults for love and protection and care. The major advantage of emotional tears is that you can target them at a specific person.”Vingerhoets says this ability to target someone could have come in hand in prehistorictimes, when humans were living among dangerous animals. Crying couldattract predators(捕食者). Tears were asafer way to get attention. In this case, it is better to use a silent signal to ask for help,”he says.

    Vingerhoets and Bylsma do frequent studies to better understand why humans cry. According to Byhma, there is still much more to discover. “It's surprising,”she says,“how much we still don't know.”

Chinese female scientist Tu Youyou won the 2015 Nobel Prize in medicine on October 5 for her discoveries concerning a novel treatment against Malaria（疟疾）. This is the first Nobel Prize given to a Chinese scientist for work carried out within China. Tu shared the prize with Irish-born William Campbell and Satoshi Omura of Japan, who were honored for their revolutionary anti-roundworm treatment. 84-year-old Tu is awarded this prize for her contribution to cutting the death rate of malaria, reducing patients' suffering and promoting mankind's health. Although she received several medical awards in the past, the 2015 Nobel Prize is definitely the most privilege reward that recognizes Tu's dedication and perseverance in discovering artemisinin（青蒿素）, the key drug that battles malaria-friendly parasites(寄生虫). However, her route to the honor has been anything but traditional. She won the Nobel Prize for medicine, but she doesn't have a medical degree or a PhD. In China, she is even being called the “three-noes” winner: no medical degree, no doctorate, and she's never worked overseas. No wonder her success has stirred China's national pride and helped promote confidence of native Chinese scientists.

The fact that Tu has none of these three backgrounds reminds us that science should be more accessible to all. One can become a scientist no matter what kind of background he or she comes from, as long as one dives into scientific research. There have been discussions on people who really love science but are never able to achieve much during their whole life. Their contributions can never be ignored. They work so hard to prove the wrong way so that the future researchers will be closer to the right one.

As the first Chinese mainland Nobel Prize Winner of natural science award, Tu's record-breaking winning also serves as a reminder to those who are too eager for instant success. Science is never about instant success. Tu spent decades on scientific research before its value is officially acknowledged. There is no way to measure how much one devotes to science and compare it with how much reward he or she may get.

    Anne LaBastille was born in New York City and grew up in New Jersey. Her first experience with the wilderness was in the Adirondacks in the northeast of New York, where she worked at a summer resort to earn money for college tuition by caring for the horses, giving riding lessons, and working as a waitress. And she has many chances to begin her adventure in the Adirondack wilderness.

    Anne returned to school in the fall, but she continued to spend as much time as she could in the Adirondacks. She grew to love her time alone in the mountains. Anne graduated from college with a bachelor's degree in conservation of natural resources and began working for the National Audubon Society in Florida as a wildlife tour leader.

    Although Anne took great pleasure in showing people the animals living in the Florida Keys and the Everglades National Park, she longed for the mountains in the northern parts of New York. Eventually, she decided to build a cabin near Black Bear Lake. Over the years, however, more and more tourists began hiking near her cabin. As a result, Anne decided to build another cabin deeper in the woods at Lily Pad Lake.

    Anne lived in the woods for most of her life. She enjoyed living alone in the woods, and her life was far too busy for her to be lonely. When she was not writing books, she wrote articles for National Geographic, Reader's Digest, and other magazines. In her later years, Anne conducted research in Guatemala on an endangered bird called the grebe. She also lectured nationwide about ecology. Besides, Anne worked with a number of organizations dedicated to conservation.

    As a respected guide, author, and conservationist, Anne not only loved the land but also had found a way to become part of it.

Editor: Today our topic is part-time job. Are they good for school children or not?

Headmaster: Certainly not. Children have got two full-time jobs already: growing up and going to school. Part-time jobs make them so tired that they fall asleep in class.

Mrs. White: I agree. I know school hours are short, but there's homework as well, and children need a lot of sleep.

Mr. White: Young children, perhaps some boys, stay at school until they're eighteen or nineteen. A part-time job can't harm them. In fact, it's good for them. They earn their pocket money instead of asking their parents for it. And they see something of the world outside school.

Businessman: You're quite right. Boys learn a lot from a part-time job. And we mustn't forget that some families need the extra money. If the pupils didn't take part-time jobs, they couldn't stay at school.

Editor: Well, we have got two for, and two against. What do our readers think?

    Nuclear power's danger to health, safety, and even life itself can be summed up in one word: radiation.

    Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can't be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can't detect them, sense them, without a radio receiver. Similarly, we can't sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.

    At very high levels, radiation can kill an animal or human being immediately by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no levels of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be serious. This is the case when only a few cells are hit, and if they are killed immediately. Your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They can grow into cancer. Sometimes this does not show up for many years.

    This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can be irradiated(辐射)and feel fine, then die for cancer five, ten, or twenty years later as a result. Or a child can be born weak as a result of radiation absorbed by its grandparents.

    Radiation can hurt us. We must know the truth.

    World-famous scientist Stephen Hawking has died at the age of 76. He was often called the most brilliant theoretical physicist since Albert Einstein. But his amazing career actually started as a young man who struggled to get around to doing his homework at Oxford University where he studied physics. He then went on to Cambridge to research cosmology, the study of the origin of universe.

    When he was 21, Hawking's life hit a big hurdle. He was diagnosed with Motor Neurone Disease. The disease causes the brain to stop sending messages to a person's muscles. At the time, doctors said he would only live for around 2 years, but he proved them very, very wrong.

    And with the help of a special wheelchair and speech computer, Hawking spent much of his time researching the beginning of the universe and black holes. His most famous discovery was probably when he demonstrated that black holes emit some radiation, which has since become known as Hawking Radiation. He also spent a lot of time thinking about what existed before the big bang.

    Hawking wrote books that explained his big ideas in ways that could be understood by the average person. In 1988 he published A Brief History of Time. It became really popular and sold more than 10 million copies. However, he wasn't just known for his books. He also had a lot of fun becoming a regular on TV screens around the world. He even had a big Hollywood film made about his life.

    Throughout his life Stephen Hawking inspired people to look beyond our planet and expand our knowledge of the universe. His family says that he'll be greatly missed and the legacy of his amazing ideas will live on.