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.”

    For years, scientist and others concerned about climate change have been talking about the need for carbon capture and storage(CCS).

    That is the term for removing carbon dioxide from, say, a coal-burning power plant's smokestack and pumping it deep underground to keep it out of the atmosphere, where it would otherwise contribute to global warming.

    However, currently, only one power plant in Canada captures and stores carbon on a commercial scale (and it has been having problems). Among the concerns about storage is that carbon dioxide in gaseous or liquid form that is pumped underground might escape back to the atmosphere. So storage sites would have to be monitored, potentially for decades or centuries.

    But scientists at Lamont-Doherty Earth Observatory at Columbia University and other institutions have come up with a different way to store CO₂ reacts with the rock to form a mineral call calcite(方解石). By turning the gas into stone, scientists can lock it away permanently. Volcanic rocks called basalts(玄武岩) are excellent for his process, because they are rich in calcium, magnesium and iron, which react with CO₂.

    The project called CarbFix started in Iceland, 2012, when the scientists pumped about 250 tons of carbon dioxide, mixed with water, about 1,500 feet down into porous basalt. Early sings were encouraging: The scientists found that about 95 percent of the carbon dioxide was changed into calcite. And even more importantly, they wrote, the change happened relatively quickly—in less than two years.

    “It's beyond all our expectations,” said Edda Aradottir, who manages the project. Rapid change of the CO₂ means that a project would probably have to be monitored for a far shorter time than a more conventional storage site.

    There are still concerns about whether the technology will prove useful in the fight against global warming. For one thing, it would have to be scaled up enormously. For another, a lot of water is needed—25 tons of it for every ton of CO₂—along with the right kind of rock.

    But the researchers say that there is enough porous basaltic rock in Iceland, including in the ocean floors and along the margins of continents. And sitting a storage project in or near the ocean could potentially solve the water problem at the same time, as the researchers say seawater would work just fine.

    Homesick is a compound word made up of HOME and SICK. You know what each word means on its own, of course. But think about what the words mean when they are used together. Homesick means SICK FOR HOME.

    Now think for a minute about SEASICK. If you change the word home in the definition(释义)to the word sea, would the definition fit SEASICK? Seasick means SICK BY THE MOVEMENT ON THE SEA. When you are homesick, the only place you want to be is at home. When you are seasick, the last place you want to be is at sea.

    Have you ever heard of a person being heartsick? Heartsick doesn't mean that something is wrong with a person's heart, people are heartsick when they are hurt deep inside and when they feel as if their hearts are broken.

    But, on the other hand, we have such compound words as handshake, handstand, and handbag. Perhaps you may write definitions for them.

    Sweat (汗水)rail its way down my cheek. It was hot, but the air was still and wet. One final play and the State Softball Championship was ours.

    I looked towards people who were watching the game. Sure enough, I found my mom. I always wished my dad were here. The farm needed his full attention, but I did not care.

    Finally, we won! State Champs! I let out a scream of happiness, fall of tears. My mom made a “V” to celebrate my success and smiled. I smiled back at her.

    We all received medals (奖牌), but I cannot remember any of it. I concentrated my thoughts on my dad, I ran to my mom, asking for her cell phone. I had to tell my dad about the happiest day of my life, and complained (抱怨）about how he did not care.

    The phone rang twice, and no one answered. My heart sank with sadness, but I tried again anyway.

    “Hello?” My dad answered.

    “Dad!” I cried. “We won State!” Silence.

    “Dad?” I could hear something on the other end. “Are you crying?”

    “I'm just really happy for you, Meggie,” he said. “And I'm sorry I couldn't be there.”

    An apology（抱歉）was all I needed. I hung up the phone feeling relaxed, and I began to understand how it must feel to be a father. I forgave him for never being there. He worked so I could play. My father loved me enough to let me experience life^ happiest moments without him.

    18-year-old Kayla Perkins explains what is in her bedroom, "I throw something on the floor and I know right where it is." However, her parents, Steve and Deborah Perkins, of McKinney, Texas, haven't caught on. Even Kayla admits that, at the worst, her room is a mess.

    Most families at some point have at least one child whose room looks like a landfill(垃圾堆). The mess can disturb the whole household. Dirty clothes pile up; dirty dishes get lost in the mess and smell bad; homework is lost; and valuable things are ruined.

    Some parents let it go, believing that a bedroom is private space for children to manage as they wish. Others lecture their children, offer rewards for cleaning, or punish them when they don't. What doesn't work, parenting experts say, is constant lectures, verbal(口头的,言语的) threats or getting very angry. Mrs. Perkins says they picked up all the clothes on Kayla's floor and hid them. They cleaned everything up. When Kayla came back to a bare bedroom, there was screaming and shouting, "How can I live without my clothes?" Mrs. Perkins asked Kayla to earn her clothes back by doing housework. These days, she keeps her room clean.

    Humour can help, too. For example, since Jessica, the 14-year-old daughter wasn't bothered by the dirty clothes all over her floor, the whole family started using her room as a place to store dirty clothes. Her attitude changed after her family did that. By the time she gave in and cleaned up her room a few days later, even she was laughing.

Parenting expert, Jim Fay, also recommends that parents first ask children in a nice way to clean up and agree on a reasonable time limit. Children often behave better if you treat them in the way you would want to be treated by your boss at work—with respect and high expectations.

A pair of researchers with Leibniz University of Hannover has demonstrated the means by which robots might be programmed to experience something similar to pain in animals. As part of their demonstration at last week's IEEE International Conference on Robotics and Automation held in Stockholm, Johannes Kuehn and Sami Haddaddin showed how pain might be used in robots, by interacting with a BioTac fingertip sensor on the end of a Kuka robotic arm that had been programmed to react differently to differing amounts of pain.

The idea of developing an artificial robot nervous system may seem contrary to all expectations, but Kuehn says doing so is important in the same way that it is good for humans to feel pain. "Pain is a system that protects us, "says Kuchn. "When we avoid the source of pain, it helps us not get hurt. "So when robots can feel and react to pain, they will become smart enough to avoid it. The more dangerous the robot registers the threat to be, the faster it will withdraw and avoid the source of danger. Additionally, Kuehn and Haddadin say humans working alongside robots that feel pain, especially those in heavy machinery, will be protected around them.

They have tested out some of their ideas using a robotic arm with a fingertip sensor that can detect pressure and temperature. It uses a robot-tissue patch(小片)modeled on human skin to decide how much pain should be felt and thus what action to take. For example, if the arm feels light pain, it slowly withdraws until the pain stops, and then returns to its original task; severe pain, meanwhile, causes the arm to go into a kind of lockdown mode until it can get help from a human operator.

Such robots are likely to raise a host of questions, of course, if they become more common —if a robot acts the same way a human does when touching a hot plate, are we to believe it is truly experiencing pain? Only time will tell of course, but one thing that is evident, Kuehn and Haddadin's work could lead to robots that are more human-like than ever.