Think of a seed buried in a pot. It's dark down there in the potting soil. There's no light, no sunshine. So how does it know which way is up and which way is down? It does know. Seeds send shoots up toward the sky, and roots the other way. Darkness doesn't confuse them. Somehow, they get it right.

    More surprisingly, if you turn a seedling (秧苗) or a whole bunch of seedlings upside down, as Thomas Andrew Knight of the Royal Society did around 200 years ago, the tips and roots of the plant will sense, “Hey, I'm upside down. Look! I. will turn my way to the right direction and do a U-turn.”

    How do they know? According to botanist Daniel Chamovitz, Thomas Knight about 200 years ago guessed that plants must sense gravity. Knight proved it with a crazy experiment involving a spinning plate.

    He attached a bunch of plant seedlings onto a disc. The plate was then turned by a water wheel powered by a local stream at a speed of 150 revolutions (旋转) per minute for several days.

    If you have been at an amusement park in a spinning teacup, you know that because of centrifugal force (离心力) you get pushed away from the center of the spinning object toward the outside.

    Knight wondered, would the plants respond to the centrifugal pull of gravity and point their roots to the outside of the spinning plate? When he looked, that's what they'd done. Every plant on the disc had responded to the pull of gravity, and pointed its roots to the outside. The roots pointed out, and the shoots pointed in. So Thomas Knight proved that plants can and do sense the pull.

    5000 B.C.— People began to farm along the Nile River in Egypt.

    2950B.C. — Egypt was first united under MENES.

    2600B.C. — The first pyramid of Egypt, the Pyramid of Djoser, was built.

    2500 B.C. — The great Pyramid of Gina was built.

    2000 B.C. — The Bantu Peoples began to migrate into central and southern Africa.

    1279 B.C. — Rameses II became pharaoh（法老）of Egypt.

    1070 B.C. — The kingdom of Kush gained its independence from Egypt.

    814 B.C. — The city of Carthage was established by the Phoenician Empire.

    715 B.C. — Kush conquered Egypt and ruled it until 662 B.C.

    650 B.C. — Cathage became independent. It grew into one of the most powerful cities on the Mediterranean Sea.

    590 B.C. — The capital of Kush was moved from Napata to Meroe.

    525 B.C. — The Persians conquered Egypt.

    332 B.C. — The Greeks led by Alexander the Great conquered Egypt.

    264 B.C. — Carthage fought in the First Punic War.

    146 B.C. —Cathage was defeated by Rome. Roman forces destroyed the city.

    30 B.C. — Cleopatra VII, the last pharaoh of Egypt, died. Egypt became part of Rome.

    Spending money on a vacation may seem like a luxury（奢侈品）—but occasionally, you have to relax yourself. Here's where to go for a good time at an unbelievable value.

    Captiva Island, Florida

    Keep it simple by looking for seashells, or bicycling, jet skiing; you can even hit the tennis courts. The Summer Getaway package offers a fourth night free and rates from $209 a night, making the average for a four-night stay $157.Kids 12 and under eat breakfast free. You'll get a coupon（优惠券）book with more than $250 in savings on resort outlets（经销店）, from watersports, island cruises and more.

    Reyjavik, Iceland

    STA Travel Beats specializes in taking travelers to music festivals around the globe. It has an eight-day tour, Icelandic Beats, that takes you to the Icelandic Geothermal spas（水疗）, UNESCO world heritage sites, and black sand beaches. End your vacation at the Secret Solstice Festival on June 18. The tour is $1,218,not including airfare.

    Malpais, Costa Rica

    You get daily surfing instruction, sunset surf session, and yoga in the outdoor, oceanfront yoga studio in a week-long tour. As you get mind, body, and spirit together, keep it going with healthy meals at the beachfront restaurant. Prices are $2,895 for shared accommodations, $3,095 for private accommodations with shared bath, and $3,595 for private accommodations.

    Waterville Valley, New Hampshire

    Waterville Valley Resort is surrounded by 100 miles of trails in the White Mountain National Forest. If you get a Freedom Pass, you can save about $100 a day during a six-day tour; the pass enables you daily to have a two-hour mountain bike rental, unlimited tennis, a round of golf, and a kayak, canoe, or paddleboard rental. Rates start at $139 a night.

    In 2007, the editors of the Oxford Junior English Dictionary, convinced that their reference work “needed to reflect the consensus experience of modern-day childhood.”banned a group of old terms used less today describing the natural world. They inserted newer and supposedly more useful words describing the digital fields that young people in habit today.

    Thus they say goodbye to “acorn”, but say hello to “attachment”. “Beech” and “bluebell” come out of the dictionary. While “blog” and “broadband” come into it. And they say farewell to “catkin” and “cowslip” because here come “celebrity” and “chat room”.

    It's possible, of course, that those Oxford editors had a good reason for their vocabular cleansing. Perhaps they had read the Cambridge University study revealing that most young children can identify Pokémon(神奇宝贝)species far more easily than they can name real-life sparrows.

    But is this simply another fight in the language war, an ongoing battle between people? Some people argue that a dictionary should model how language works best, while some people insist that it should capture how language works now.

In Britain, some citizens felt justified in fighting back against the decision of the Oxford editors. The protest of the thinning of the word herd almost immediately attracted more than200, 000 signatures.

    Susie Dent, author of Modern Tribes：The Secret Languages of Britain, is doing everything in her power to guarantee “the old markers of time”. “Fortnight”(fourteen nights, or two weeks)is among her cherished favorites.

    Thanks to them, I can now show off my knowledge that a “snollygoster” is a “shrewd person, especially a politician”.

    Visit the Newseum During "Museum Day"！

    Museum Day is an annual celebration of boundless curiosity hosted by Smithsonian magazine. Participating museums and cultural institutions across the country provide free entry to anyone presenting a Museum Day ticket. The Museum Day ticket provides free admission for two people.

    Here is some information about a popular museum — the Newseum.

    EVENT DETAILS

    Registration: free tickets will be available for the public to download on December 15 via the link: https://www.smithsonianmag. com/museumday/museum-day-2018/.

    Advanced registration is requested so that the museum sites know how many people to expect. If you don't register beforehand you may still be admitted the day of the event, but no guarantee for admission. All are welcome to attend including children and groups.

    Meeting Point #1: From 7:45 – 8:00 some volunteers will be in the Starbucks at 325 7th St NW before walking 2 blocks to the Newseum.

    Meeting Point #2: Outside the Newseum's Pennsylvania Avenue entrance. The Newseum opens at 9:00 am. However, as this is an extremely popular event we highly recommend arriving as early as possible, by 8:15 if you can, to bypass the masses that will show up later in the day.

    Meeting Point #3: Once the museum opens we recommend immediately heading to the 6th floor to avoid the masses since most people start on the 1st floor. On the 6th floor, the Hank Greenspun Terrace, which overlooks Pennsylvania Avenue and the U. S. Capitol, has one of the best views in Washington, DC. After that you can proceed through the museum's exhibits starting on the 6th floor and working our way down. The Newseum is open until 5:00 pm and guests are free to arrive and depart whenever they like.

Growing up in poverty in rural Kenya,Nelly Cheboi watched her single mother work tirelessly so she could attend school. 

From an early age,she realized that her family,along with others like hers in their village, was1 a cycle that left them little hope. Cheboi attended college.2 a scholarship in the United States,worked odd jobs to support her family,and discovered her3 for computer science. She4 the success in finding jobs to her computer literacy. She knew she wanted to share it with her5 back home. 

Today,she's giving 4,000 kids the chance for a6 future through her nonprofit, TechLit Africa. The organization uses recycled7 to create technology labs in schools in rural Kenya. 

In 2018,she began8 recycled computers. She started small,carrying the machines to Kenya and9 customs fees and taxes herself. TechLit Africa now works with shipping companies to10 the donated computers so it's more cost11 . The donated hardware is12 to partner schools in rural Kenya,where students aged 4 to 12 receive daily classes and13 opportunities from professionals and gain skills that will help improve their education and prepare them for future jobs. 

"My hope is that when the first TechLit kids graduate from high school,they're able to get a job online14 they will know how to code,"Cheboi said. "The world is your oyster when you are educated. By bringing the resources,by bringing these skills,we are15 the world to them. "