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.

    Field Trip Day

    On Friday, May 16, our class will take a field trip to North Park Zoo. The zoo has lions, elephants, and other interesting animals. Many of the animals we have been studying will be there for us to closely examine.

    Our class will be divided into six teams. Each team will have five students and one leader. The leaders are listed in the table.

    What You Need to Know

    The cost is $1.00 for students to enter the zoo. We will leave the school at 9:00 a.m. and return at 2:30 p.m.

    On the morning of the trip, the students will be divided into teams. One student from each team will receive a camera. The cameraman will take pictures of the team, the animals, and other fun sights at the zoo.

    All members should wear blue shirts. Be sure to wear comfortable shoes because we will be walking all day. Please bring a bag lunch and a drink. We will have a picnic at the park inside the zoo. Bring a healthy snack, such as a piece of fruit and a drink, for later in the day.

    When we are at the zoo, always remain with your team. Do not leave the team without asking permission from the team leader.

    Feeding the Animals

    The ONLY animals that students are allowed to feed are those in the children's Zoo. Special food can be bought at the zoo for 25 cents and given to these animals. Do not feed your lunch to them. It is not food for the animals.

    I sat with my friend in a well-known coffee shop in a neighboring town of Venice. As we enjoyed our coffee, a man called the waiter and placed his order, “Two cups of coffee, one on the wall.” We got interested and observed that he was served with one cup of coffee but he paid for two. As soon as he left, the waiter attached a piece of paper to the wall saying “A Cup of Coffee.” Similar occasions took place twice while we were there. It seemed that this gesture was quite normal at this place. However, it was something unique and confusing for us.

    After a few days, when we again enjoyed coffee there, a man entered. The way this man was dressed did not match the standard or the atmosphere of this coffee shop. Poverty was evident from his looks. As he seated himself, he looked at the wall and said, “One cup of coffee from the wall.” The waiter served coffee to this man with respect and dignity. The man had his coffee and left without paying. We were amazed to watch all this when the waiter took off a piece of paper from the wall and threw it in the dustbin.

    Now it was no surprise for us; the matter was very clear. The great respect for the needy shown by people in this town moved us to tears.

    Coffee is not a necessity. However, the point is that when we take pleasure in any blessing, maybe we also need to think about those people who also appreciate that specific blessing but cannot afford.

    Note the waiter, who gets the communication going between the affording and the needy with a smile on his face. Think about the man in need: he enters the coffee shop without having to lower his self-dignity; he has a free cup of coffee without asking or knowing about who has given this cup of coffee to him; he only looked at the wall, placed an order for himself, enjoyed his coffee and left. Besides, we need to remember the role played by the wall that reflects the generosity and care of people in this town.

    Sandra Cisneros was born in Chicago in 1954 to a Mexican American family. As the only girl in a family of seven children, she often felt like she had "seven fathers," because her six brothers, as well as her father, tried to control her. Feeling shy and unimportant, she retreated (躲避) into books. Despite her love of reading, she did not do well in elementary school because she was too shy to participate.

    In high school, with the encouragement of one particular teacher, Cisneros improved her grades and worked for the school literary magazine. Her father encouraged her to go to college because he thought it would be a good way for her to find a husband. Cisneros did attend college, but instead of searching for a husband, she found a teacher who helped her join the famous graduate writing program at the University of Iowa. At the university's Writers' Workshop, however, she felt lonely－a Mexican American from a poor neighborhood among students from wealthy families. The feeling of being so different helped Cisneros find her "creative voice".

    "It was not until this moment when I considered myself truly different that my writing acquired a voice. I knew I was a Mexican woman, but I didn't think it had anything to do with why I felt so much imbalance in my life, but it had everything to do with it! That's when I decided I would write about something my classmates couldn't write about."

    Cisneros published her first work, The House on Mango Street, when she was twenty-nine. The book talks about a young Mexican American girl growing up in a Spanish-speaking area in Chicago, much like the neighborhoods in which Cisneros lived as a child. The book won an award in 1985 and has been used in classes from high school to graduate school level. Since then, Cisneros has published several books of poetry, a children's book, and a short-story collection.

    When an earthquake hit a small town, many houses fell down. After the earthquake, all the newspapers reported many stories about some of the families who were in trouble.

    One Sunday, when I was reading a newspaper, a special picture touched me. It gave the clothing sizes of each family member. I thought that this would be a good chance to teach my children to help those who were less lucky than themselves. I said to my seven-year-old twins, Brad and Brett, and three-year-old Meghan, "We have so much, and these poor people now have nothing. We'll share what we have with them."

    I filled a box with foods and clothes. While I was doing this, I encouraged the boys to choose their toys and donate some of their less favorite things. Meghan watched quietly as the boys took out their old toys and games and put them together. Then she walked away. A few minutes later she came back with Lucy, her much-loved doll. She put the doll on top of the other toys. "Oh, dear," I said. "You don't have to give Lucy. You love her so much." Meghan said, "Lucy makes me happy, Mommy. Maybe she'll make another little girl happy, too."

    I looked at Meghan for a long moment. She taught me a lesson. It's easy to give something that we don't want any more, but hard to give what we cherish (珍爱), isn't it?

Smart Cameras to Help You Take Better Photos

    Google Clips

    One of the latest to launch is Google Clips. It is designed to be put somewhere in a room to take pictures by itself. It can also be attached to an object or a person's clothing.

    Google says machine learning helps the camera choose the best times and situations for taking pictures and videos. Interested buyers can join a waiting list to be informed when it is on the market.

    GoPro Hero

    GoPro also uses machine learning to power its QuikStories characteristic. This tool takes existing photos and videos and automatically creates a finished video piece, complete with music and effects.

    Snap Spectacles

    Messaging app Snapchat sells a pair of sunglasses with a built-in camera that can record short videos with the push of a button. Snap Inc. says the product, called Spectacles, is designed to "catch the moment, without taking you out of it."

    The glasses can record short video clips that can be shared with Snapchat users. Snap Inc. has started selling its Spectacles sunglasses online in the United States.

    Apple iPhone X

    Apple's new iPhone X is being launched with its new Face ID system that it says will unlock the phone just by having the user look at it. This replaces the Touch ID on previous ones that used a fingerprint to unlock the phone.

    Apple says the system works by projecting more than 30,000 dots on the face to create a kind of map. Apple says its facial recognition is even secure enough to allow payments through its Apple Pay service.