In the traffic lights,red means "stop",green means "go",and yellow means "hurry": Why those colors, though? Why not blue,purple,and brown?The following are transponded from others WeChat.

●Red is an inherited symbol from railroads

    Red symbolizes danger in many cultures,which makes sense,considering it has the longest wavelength of any color,meaning you can see it from a greater distance than other colors.Red has meant "stop" since long before cars existed,with railway signals use of red dating bake to the days when mechanical arms lifted and lowered to indicate whether the rail ahead was clear.So that one's simple.

●Green meant "caution" at first

    Green's role in lights has actually changed dramatically over time.Its wavelength is next to (and shorter than) yellow's,meaning it's still easier to see than any color other than red and yellow.Back in the early days of railway lights,green originally meant "caution",while the "all-clear" light was,well,clear or white.Trains,of,course,take an unlimitedly long time to stop,and legend has it that several disastrous collisions happened after an engineer mistook stars in the night horizon for an all-clear.Thus,green became "go",and for a long time,railways used only green and red to signal trains.

●Yellow means "caution" because it's almost as easy to see as red

    From the earliest days of motoring up until the mid-1900s,not all stop signs were red-many were yellow, because at night it was all but impossible to see a red stop sign in a poorly lit area.The yellow stop-sign craze began in Detroit in 1915,a city that five years later installed its first electric traffic signal,which happened to include the very first amber traffic light,at the corner of Michigan and Woodward Aves.

    Feeling sad is an important part of human nature.

    Jerome Wakefield, a professor at New York University, mentions that feeling down after your heart is broken is normal and may even be beneficial. Recently, Wakefield's students have been coming up to him because their parents are pressuring them to get help for their sadness; often the kids want no part of it. Rather than “listen to medicine,” they want to listen to their hearts. He believes these students' reaction represents an important part of human nature.

    Professor Diener, who has studied happiness for a quarter century, finds that the Scots and many other peoples like being sad, and don't appreciate being told they should be happier. “They say too much happiness might not be such a good thing, no matter where it comes from,” says Diener. He believes it's wrong for the “happiness industry” to send the message that not only can we all be happier, but we have a duty to be so. He argues that what is considered normal sadness is something we shouldn't avoid.

    Eric Wilson, a professor at Wake Forest University, made every effort to smooth out his habitual frown and wear a sunny smile, since a happy expression can lead to happy feelings. He even tried to be enthusiastic. When neither of these made him happy, he concluded that such a happiness movement was no good for him at all. Americans, love for happiness, he writes, creates an environment where sadness is not valued.

    These researchers believe the problem of continuous, extreme happiness should not be surprising, since negative emotions developed for a reason. Fear warns us against the presence of danger, for instance. Sadness, too, seems to be part of our DNA: monkeys, dogs and elephants all display something that looks like sadness. Being “up” all the time can cause you to play down very real threats.

    They believe that only by experiencing sadness can we experience the fullness of the human condition. Their studies show that when you are in a negative frame of mind, you become more logical and more creative. Abraham Lincoln was not limited by his dark moods, and Beethoven composed his later works in a sad state. Vincent van Gogh, Emily Dickinson and other artistic giants saw the world through a glass darkly.

    People who are somewhat unhappy are more motivated to improve both their own lot and the lot of their community. In contrast, people at the top of the happiness charts feel no such urgency. “If you're totally satisfied with your life,” says Diener, “you don't feel like working for change. Be careful when people tell you that you should be happier.”

    My grandfather died more than twenty-five years ago. I was fifteen then. He was kind, strong, fair, and very funny. When I was a young musician, he was my biggest fan. I played my violin for him when he visited, and he loved everything, but each time he had one request. “Could you play Amazing Grace%” he asked, full of hope and with a twinkle in his eye, because he knew my answer was always, “I don't know that one!” We went through this routine at every major holiday, and I always figured I'd have time to learn it for him later.

    About the time I entered high school and started guitar, Grandpa got cancer. The last time I saw him alive was Thanksgiving weekend in 1985. My mom warned us that Grandpa didn't look the same anymore and that we should prepare ourselves. For a moment I didn't recognize him. He looked so small among all the white sheets. We had all gathered in Ohio for the holiday, and I'm sure we all knew we were there to say good-bye. I can see now that Grandpa held on long enough to see us each one more time. I remember how we ate in the dining room and laughed and talked while Grandpa rested in his hospital bed. I wonder if it was sad for him to be alone with our voices and laughter. Knowing Grandpa, he was probably content.

    The next morning, I found my moment alone with him. I pulled out my guitar, tuned to his appreciative gaze, and finally played for him Amazing Grace. I had worked on it for weeks, knowing it never mattered whether I actually played it well and choosing not to believe as I played that it was my last concert for my biggest fan. The cancer had stolen his smile, but I saw joy in his eyes. He held my hand afterward, and I knew I had done something important.

    I argued with people all through college about my music major. I was told by strangers that music wouldn't make me any money and it wasn't useful like being a doctor. But I know first-hand that with music I was able to give my grandpa something at a point when no one else could.

    Why do you go to the library? For books, yes—but you like books because they tell stories. You hope to get lost in a story or be transported into someone else's life. At one type of library you can do just that—even though there's not a single book.

    At a Human Library, instead of books, you can "borrow" people. People with unique life stories volunteer to be the "books." For a certain amount of time, you can ask them questions and listen to their stories, which are as fascinating as any you can find in a book. (If you attend, make sure to review the habits that make you a good listener.) Many of the stories have to do with some kind of depressing topic. You can speak with a refugee, a soldier suffering from PTSD (创伤后遗症), a homeless person and a woman living with HIV. The Human Library encourages people to take time to truly get to know and learn from someone they might otherwise make a snap judgement about. According to its website, the Human Library is "a place where difficult questions are expected, appreciated and answered."

    The Human Library Organization came to be in Copenhagen, Denmark in 2000. Romni Abergel and his colleagues hosted a four-day event during a major Northern European festival. After the success of this event, Abergel founded the Human Library Organization, hoping to raise awareness among youth about depression, which has been growing ever since.

    Though there a few permanent human libraries, most aren't place at all, but events. Though many do take place at physical libraries, you don't need a library card—anyone can come and be part of the experience. There have been human library events all over the globe, in universities and in pubs, from Chicago to Tunis to Edinburgh to San Antonio. Check out the organization's Facebook page to see when the Human Library might be arriving near you.

    During your four years in the college, you'll have many exciting choices to make, the first of which will be your course selection for your first semester. The beauty of this choice is that you can't go wrong! No matter which one of our First-Year Options you select to apply for, you will create a rich intellectual experience to begin your college career.

    Option 1: Liberal Arts Seminar

    The Liberal Arts Seminar is a multidisciplinary(多学科的)course that explores the cultural history of the Mediterranean through fictional and nonfictional books.

Fall schedule: When Registration opens, you will select between one and four additional courses to complete your schedule.

    Option 2: FLL Hager Scholars Program

    The FLL Hager Scholars Program is designed with our most ambitious students of languages and linguistics in mind, and is designed to create for them both a sense of community and opportunities for intellectual growth.

    Fall schedule: When Registration opens, you will select between one and three additional courses to complete your schedule.

    Option 3: Ignatius Seminars

    Offered only in the first semester, Ignatius Seminars introduce students to the depth and diversity of Georgetown's dynamic intellectual community.

    Fall schedule: When Registration opens, you will select three or four additional courses to complete your schedule.

    Option 4: Traditional First-Year Academic Program

    With this program, you'll take your first step into the college's rich and varied core courses and explore your fields of interest in free optional coursework.

    Fall schedule: When Registration opens, you will build a schedule of four or five additional courses from the full college curriculum.

About two years ago, Coronavirus(新冠病毒) showed up(出现). So many great people are fighting it to protect(保护) us. One of them is Zhong Nanshan. He's 84 years old, but he's still fighting the virus. Thanks to them, China is getting better(情况好转). But this virus is really dangerous. We must be careful all the time. Here are some ways to protect ourselves.

Wear a face mask(口罩).

Wash your hands often.

Don't touch your face, eyes, nose and mouth before washing your hands.

Do some exercise to keep healthy.

China is a very big and old country. Over 5, 000 years, we faced many problems. Fighting this virus is just another one of those problems. At last(最终), we will win.