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.”

    On the last day before Christmas, I hurried to the supermarket to buy Christmas gifts. In the supermarket, I noticed a little boy, holding a doll and looking so sad. He turned to the old woman next to him, “Granny, are you sure I don't have enough money?” The old lady replied, “You know we don't have enough money to buy this doll, my dear.” Then she left for something else and the boy still stood there.

    Finally, I went to the boy and asked him who he wanted to give this doll to. “It is the doll that my sister wanted so much for this Christmas. She was so sure that Father Christmas would bring it to her.”

    I told him that maybe Father Christmas will bring it to her. But he replied to me sadly, “No, Father Christmas cannot bring it to her where she is now. I have to give the doll to my mother so that she can give it to her when she goes there. My sister has gone to be with God. Daddy says that Mummy will also go to see God very soon, so I thought that she could bring the doll with her to give it to my sister.”

    Hearing this, I quickly reached into my wallet and took a few notes and said to the boy, “What if we checked again, just in case if you have enough money?”

    “OK,” he said, “I hope that I have enough.”

    I added some of my money to his without his seeing and we started to count it. There was enough for the doll.

    The little boy said, “Thank God for giving me enough money.”

    Then he looked at me and added, “I prayed to God yesterday before I slept to make sure I have enough money to buy this doll. He heard me.”

    Obviously, most people who try to lose weight generally focus all or most of their attention on the food they eat. But what about their behavior? Are there habits they could be breaking that would also help them lose weight?

    According to the Ohio State University Extension, which summarized the findings, the researchers learned people who routinely ate breakfasts, lunches, and dinners tended to have more success losing weight than people whose eating schedules were irregular. As a bonus, they were also more likely to eat a larger quantity of fruits and vegetables.

    One activity that brought a disaster to people who wanted to lose weight was watching television, particularly if they ate while watching TV--especially if they ate while watching TV after 7 p.m. People who did these things, including simply watching a lot of television, tended to have a higher body mass index (BMI), as well as a higher intake of fat and sugars.

    Those who ate out a lot also tended to take in more fat and sugars, while eating fewer fruits and vegetables. For the purposes of the study, eating away from home was defined not only as eating in restaurants but also eating food provided by an employer or colleagues at work, buying food at convenience stores or gas stations, or buying food for fund-raisers.

    Finally, the best results were achieved by those motivated people who kept writing the track of the amount and type of exercise they did and how many calories they ate, who planned meals, and used meal replacements. Those who did these things the most generally lost more weight, ate less fat and sugars, ate more fruits and vegetables, and engaged in more physical activities.

So cutting out all those high-calorie snacks will help you lose weight. If so, apparently, will change some of your habits and behavior.

    Tiny as they are, bats have the ability to “see” in the dark by using a special skill called echolocation(回声定位法). They make noises and wait for sound waves, or an echo, to bounce(反弹) back off objects. They can tell the distance of various objects by how quickly the sound waves bounce back off them. If no sound bounces back, they can then fly forward.

    This special ability has been simulated in the human world for a long time, such as in submarines and planes, whose sonar(声呐) systems are somewhat similar to echolocation. But apart from helping vehicles “see” where they are, what if blind people could use echolocation for themselves? It turns out, some already are.

    American Daniel Kish, who is blind, is known as “Batman”. This isn't because he walks around in a cape and a mask, but because he has a bat-like ability to locate where he is through sharp clicks he makes by moving his tongue against the roof of his mouth. Kish is so skilled at echolocating that he can ride a bike and hike on his own.

    Recently, research carried out at the University of Durham in England shed some light on the power of human echolocation.

    Kish worked with a group of scientists who studied the way blind people listen to the echoes that they produce from clicks.

    The team, which conducted experiments with other volunteers, found that people were capable of hearing even very faint echoes, ones far fainter than had been previously thought.

    Speaking to The Independent, Lore Thaler, lead scientist of the group, said, “We found that in some conditions, they were really faint – about 95 percent softer than the actual clicks, but the echolocators were still able to sense this.”

    Andrew Kolarik of the University of Cambridge is another expert in echolocation. Reacting to the Durham study, he told BBC News that echolocation “can be very useful at providing information at face or chest height” and could help people “avoid objects like low hanging branches that might not get detected by the cane or a guide dog”.

    Although Kish's skill is remarkable, there's hope for other blind people who want to use echolocation. According to BBC News, echolocation is a skill blind people can acquire and develop, just like learning a language. As Kolarik said: “Teaching echolocation skills could provide blind people with the means of exploring new places.”

    2019 Oscars Academy Award Nominees (提名) for Best Picture

    Black Panther

    Type: Adventure

    Running Time: 134 min.

    Release Date: February 16, 2018

    Current rank: ★★★★

    Director: Ryan Coogler

    Actors: Chadwick Boseman, Michael B. Jordan

    With his father having died in Captain America: Civil War, T'Challa is the new ruler of the advanced kingdom of Wakanda. As the king, whenever a challenger for the crown announces his intentions, he must give up his powers and take them on in a physical challenge.

    The Favorite

    Type: Drama

    Running Time: 120 min.

    Release Date: November 30, 2018

    Current rank: ★★★

    Director: Yorgos Lanthimos

    Actors: Emma Stone, Rachel Weisz

    In the early 18th century, with England and France at war, a fragile Queen Anne occupies the throne as her close friend Lady Sarah Churchill governs the country in her stead, while tending to Anne's ill health and changeable temper.

    Green Book

    Type: Drama

    Running Time: 130 min.

    Release Date: November 21, 2018

    Current rank: ★★★★★

    Director: Peter Farrelly

    Actors: Viggo Mortensen, Mahershala Ali

    Tony Lip, an uneducated Italian-American who's known for using his fists to get his way, is hired to drive world-class, famous pianist Don Shirley on a concert tour from Manhattan to the Deep South. They must rely on the “Negro Motorist Green Book” to guide them to the few settlements that were then safe for blacks.

    A Star is Born

    Type: Musical

    Running Time: 135 min.

    Release Date: October 5, 2018

    Current rank: ★★★★

    Direct: Bradley Cooper

    Actors: Bradley Cooper, Lady Gaga

    When country music star Jackson Maine stops at a bar for a drink after a concert, he's both entertained and attracted by young nightclub singer Ally. He discovers that she writes songs as well as being a talented singer, but hasn't had a break because of her looks.

    A new mom from Michigan headed for the airport Thursday, nervous about flying alone with her -month-old. When her daughter started crying even before take-off her fears for the flight — to surprise her husband, a US Army soldier at Fort Rucker Alabama — seemed acceptable.

    The couple seated next to her reacted just as Rebekka Garvison had feared, looking visibly unhappy about sitting next to a fussy(难以取悦的)baby. Ms. Garvison moved to a new seat, hoping it would help. When the baby's cries continued, the woman sitting next to her asked if she could try.

    Garvison later described in a grateful Facebook post how the woman, Nyfesha Miller, had the magic touch with her baby. "As soon as she had her, Rylee was looking out the window and stopped crying," Garvison recalled. "When we got in the air she fell right asleep and slept in her lap the whole flight until we got to our gate? Garvison told The Huffington Post she has been in touch with Ms. Miller almost daily since the flight.

    Garvison's post has been shared more than 84,000 times, and received hundreds of warm comments. "Years ago, the same kind of thing happened to me," wrote one mother. "It was a seven-hour flight and I had my ten-month-old little boy with me. A nun （修女）was sitting beside me and she walked him up and down the passage when he got fussy. It was such a relief for me and is something I will never forget."

    Not everyone has had happy experiences with baby air travelers. One airline is considering opening a "baby class" for airplanes with flight attendant nannies（保姆）, reported The Christian Science Monitor's Meredith Hamilton. For now, parents can hope to be seated beside someone like Ms. Miller on their next flight. "Nyfesha Miller, you will never understand how happy this act of kindness has made my family." wrote Garvison.