See a cellphone cover that you like on Taobao? Forget about placing an order, paying the bill online and waiting for days for it to be delivered to you. In the near future, you'll be able to get it in minutes just by hitting “print” on your computer.

    You might find it hard to believe that you could actually “print” an object like you would a picture. But it is not that hard to understand how it would work. Just as a traditional printer sprays ink onto paper line by line, modern 3D printers spread material onto a surface layer by layer, from the bottom to the top, gradually building up a shape.

    Instead of ink, the materials the 3D printer uses are mainly plastic, resin(树脂) and certain metals. The thinner each layer is—from a millimetre to less than the width of a hair—the smoother and finer the object will be.

    This may sound like a completely new technology, but the truth is that 3D printing has been around since the late 1980s. Back then, it was barely affordable for most people, so few knew about it.

    Last year, though, saw a big change in the 3D printing industry—printers became much cheaper. For example, 10 years ago a desktop 3D printer might have cost ￡20，000, while now they cost only about ￡1，000, according to the BBC.

    Taken out of the factory and introduced to more diverse and common uses, 3D printing can create just about anything you can think of—flutes , bikinis, jewelry, aircraft parts and even human organs. In fact, scientists from Cornell University in New York have just made an artificial ear using a 3D printer, according to Science Daily. The fake ear looks and acts exactly like a natural one.

    However, as 3D printing becomes more common, it may bring about certain problems—such as piracy. “Once you can download a coffee maker, or print out a new set of kitchen utensils (餐具) on your personal 3D printer, who will visit a retail  store again？” an expert in 3D printing told Forbes News. Even more frightening, what if anyone in the world could use a 3D printer to print out a fully functioning gun?

    Nobody is sure where and when the expression “apple-pie order” began. Some say that Scottish and English writers used the expression a long time ago. Others say it was first used in the northeastern American states known as New England. The housewives of New England cut their apples in even slices. Then they filled pie pans with them in an organized way, row upon row. As one writer said, the women of New England loved to have everything in its place. This perhaps explains why it generally is believed that the expression “apple-pie order” began in New England.

    Another old expression, “apple of discord”, comes from ancient mythology(神话), however. The myth says that all the gods and goddesses were sitting around the table to celebrate the marriage of Thetis and Peleus. One of the goddesses-Discord was a troublemaker. She threw away a golden apple on the table to be given as a prize to the most beautiful goddess.

    At one time, the tomato was called a love apple. That was a mistake. This is how the mistake happened: In the sixteenth century, Spain brought the tomato from South America after Spanish explorers had landed there. Spain then sold the tomato to Morocco. Italian traders carried it on to Italy. The Italian name for the tomato was “pomo di Moro” meant “d'amour” -the French word for love. And so “pomo di Moro” became the apple of love.

    People believe many things about the apple. One belief is that it has great powers of keeping people healthy. A very common expression is "an apple a day keeps the doctor away."

    Another belief is based on fact. The expression is "one rotten apple spoils the barrel." When an apple begins to go bad, it ruins all the other apples around it in the container. The expression has come to mean that one bad person in a group can cause everyone to act bad.

    Lawns（草坪）are some of the most common things in the world until you really start thinking about them. That's when you realize that they make no sense. Why do people keep these uninteresting, pointless little plants outside their homes? They're not beautiful like flowers, they don't provide food and you have to take care of them constantly.

    Israeli bestselling author Yuval Noah Harari thought these deeds were weird too. He looked into their history and ended up with an interesting story.

    No one considered putting patches of grass outside their homes in ancient times. That changed in the Middle Ages, when French and English kings and nobles started putting patches of grass at their castle entrances.

    “Well-kept lawns demand land and a lot of work,” wrote Harari in his book. “In exchange, they produce nothing of value.” Peasants could never afford to waste their time or land on lawns, so these lawns were a perfect status symbol（身份的象征）for nobility（高贵）.

    When the Industrial Revolution began in the 18th and 19th centuries, the middle classes started being able to afford their own suburban（郊区的）houses. And guess what became the suburban status symbol? A perfectly kept lawn.

    The popularity of lawns continued to grow, taking over public event spaces and sports. In the past, people played sports on all kinds of surfaces—dirt, ice, sand. But in the last couple centuries, they made the switch to green grass.

    “Grass is nowadays the most widespread crop in the USA after corn and wheat,” Harari continued. Lawns spread beyond Europe and the U.S, and they're now status symbols around the world.

    Suburban people may not realize it, but they care for lawns just because centuries ago, French and English kings wanted to show off by intentionally planting something useless. It's strange that people should continue to spend so much time and money on what's really a leftover（遗留物）from the Middle Ages. When you plan your house, you can shake off（摆脱）the cultural leftover and imagine for yourself a rock garden or some other new creation.

    Spring is a wonderful season to celebrate rebirth and new life. The long, cold winter is over. The weather is warmer and sunnier. The trees again have leaves and the flowers are blooming. The season represents hope, joy and beauty. At this time, many people think of this classical music piece—Spring, which shows happiness. Italian composer Antonio Vivaldi wrote it in the seventeen hundreds.

    However, not all songs about spring are happy. This song written and sung by K.D. Lang is about dreaming of spring in cold dark places. She recorded I Dream of Spring in 2008.

    Richard Rodgers and Oscar Hammerstein wrote It Might as Well Be Spring for the movie State Fair in 1945.Frank Sinatra sings it. It is a feeling of restlessness or excitement brought on by the coming of spring. Richard Rodgers also wrote Spring Is Here, this time with Lorenz Hart. Ella Fitzgerald sings this song about feeling lonely during this season.

    Frank Loesser wrote the sad song, Spring Will Be a Little Late This Year. Why has the season been delayed? Because the singer's lover has left her. Sarah Vaughn released(发行) her version of the song in 1953.

    By now you may be thinking, "Enough with the sad songs, already！"OK ,then how about a cowboy song? Gene Autry was one of the America's most famous singing cowboys. He recorded When It's Spring time in the Rockies in 1937.

    And finally, we'll leave you with a sunny song called Up Jumped Spring. Freddie Hubbard wrote this jazz song in 1977 and Billy Taylor Trio performs it.

    Keeping the memory in shape is important at any age, but it requires a bit more work as we grow. There are some simple activities that can improve your memory.{#blank#}1{#/blank#}

    Awaken your senses.

    Use your senses to help your memory store(储存) needed information. {#blank#}2{#/blank#}You can ask yourself like this: Is the sky a light blue or deep purple? The more involved(参与的) you can be in the information, the easier it is for your brain to store it.

    Use imagination and relation.

    Trying to remember names? Let's say you meet a man named Frank Parker. {#blank#}3{#/blank#}Tie the two together by picturing Frank dressed up in a hot dog costume(服装) parking his car in the parking lot. Now each time you see Frank, you should easily recall his name.

    Breathe deeply and relax.

    {#blank#}4{#/blank#}Relax, breathe deeply and slowly and let your mind ease up for a minute. Being relaxed makes it easier for information to be both stored and remembered.

    {#blank#}5{#/blank#}

    When you come upon something you need to remember, say to yourself, “Hey, pay attention and remember this!” You are giving yourself a wake-up call as well as giving your mind a marker that it can use to help in storing the new information.

A. Give yourself an order.

B. Get a good night's sleep.

C. Here are four of them to get you started.

D. Picture a hot dog for Frank and a car for Parker.

E. For example, note the colors of a picture you want to remember.

F. When we try hard to remember something we often become nervous.

G. The way you live influences not only your physical health but also your memory.

Babies made from three people approved in UK

    Babies made from two women and one man have been approved by the UK's fertility regulator. The historic and controversial move is to prevent children from being born with deadly genetic diseases.

    Doctors in Newcastle — who developed the advanced form of In Vitro Fertilization or IVF (人工授精) — are expected to be the first to offer the procedure and have already appealed for donor eggs. The first such child could be born, at the earliest, by the end of 2017.

    Some families have lost multiple children to incurable mitochondrial (线粒体的) diseases, which can leave people with insufficient energy to keep their heart beating.

    The diseases are passed down from only the mother, so a technique using a donor egg as well as the mother's egg and father's sperm has been developed.

    The resulting child has a tiny amount of their DNA from the donor, but the procedure is legal and reviews say it is ethical (伦理的) and scientifically ready.

    "It is a decision of historic importance," said Sally Cheshire, chairwoman of the Human Fertilisation and Embryology Authority (HFEA). "I'm sure patients will be really pleased by what we've decided today."

    But some scientists have questioned the ethics of the technique, saying it could open the door to genetically-modified(转基因) 'designer' babies.

    The HFEA must approve every clinic and every patient before the procedure can take place. Three-person babies have been allowed only in cases where the risk of a child developing mitochondrial disease is very high.

    Prof Mary Herbert, from the Newcastle Fertility Centre, said, "It is enormously pleasing that our many years of research in this area can finally be applied to help families affected by these devastating diseases".

    "Now that we are moving forward towards clinical treatments, we will also need donors to donate eggs for use in treatment to prevent affected women transmitting disease to their children."

    Prof Sir Doug Turnbull, the director of the Welcome Centre for Mitochondrial Research at Newcastle University, said, "We are delighted by today's decision. We will also provide long-term follow up of any children born."

    NHS England has agreed to fund the treatment costs of the first trial of three-person IVF for those women who meet the HFEA criteria, as long as they agree to long-term follow up of their children after they are born.