Getting less sleep has become a bad habit for most American kids. According to a new survey(调查) by the National Sleep Foundation, 51% of kids aged 10 to 18 go to bed at 10 pm or later on school nights, even though they have to get up early. Last year the Foundation reported that nearly 60% of 7- to 12-year-olds said they felt tired during the day, and 15% said they had fallen asleep at school.

    How much sleep you need depends a lot on your age. Babies need a lot of rest: most of them sleep about 18 hours a day! Adults need about eight hours. For most school-age children, ten hours is ideal(理想的). But the new National Sleep Foundation survey found that 35% of 10- to 12-year-olds get only seven or eight hours. And guess what almost half of the surveyed kids said they do before bedtime? Watch TV.

“More children are going to bed with TVs on, and there are more opportunities(机会) to stay awake, with more homework, the Internet and the phone,” says Dr. Mary Carskadon, a sleep researcher at Brown University Medical School. She says these activities at bedtime can get kids all excited and make it hard for them to calm down and sleep. Other experts say part of the problem is chemical. Changing levels of body chemicals called hormones not only make teenagers' bodies develop adult characteristics, but also make it hard for teenagers to fall asleep before 11 pm.

Because sleepiness is such a problem for teenagers, some school districts have decided to start high school classes later than they used to. Three years ago, schools in Edina, Minnesota, changed the start time from 7:25 am to 8:30 am. Students, parents and teachers are pleased with the results.

    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?

    Are you afraid of moving up to senior high school? It is a completely new experience, but you shouldn't worry. We've got a guide to help you.

    You're not alone. Remember that everybody else in your year is in the same boat. You may not notice it, but they're just as nervous as you are.

    Moving to senior high school is a chance, not a problem. Things are different, and all you need to do is to be polite and learn the new rules.

    The teachers will help. If you don't know what to do or are worried about something, then ask for help. Teachers are probably the best people to turn to, because they have experience in helping new students. Pay attention to what your teachers say.

    Everything changes. There are lots of differences between junior high school and senior high school. You will have your lessons with different teachers in different rooms. You will have homework for different subjects on different days, so make sure you get organised. Make sure you know which rooms your classes are in and which days you have your different subjects on.

Other points:

    If you've got an older brother or sister at the school, then ask them for advice.

    Be yourself! It sounds simple, but things will become better if you just act naturally.

    Having early nights makes a difference. You'll also find it easier to get up in the morning!

    Whether you're on a long road trip or stuck in traffic while driving home from work, a low phone battery (电池) could mean disaster for the bored driver. At first, it may seem harmless to plug your phone into your car's USB port. But unless you're desperate, charging your phone in your car might be a big mistake.

    Why? First, the USB port in your vehicle probably provides less electricity than your phone really needs to charge. As a result, your phone might stop working while it charges, or worse—hardly charge at all.

    Brad Nichols, a technician at Staymobile, told Reader's Digest. “This is mostly due to the fact the phone is using more power than the car charger is supplying it.”

    Nichols also says that your phone could receive too much power, especially if you're using a “Cigarette Lighter” port to charge up. Most Cigarette Lighters can supply up to 10 amps (安培), while most chargers use one to three amps. A damaged charger can provide inconsistent power to the phone, leading to sudden power increase that could cause damage to the inside parts, or on the rare occasion, destroy it.

    Charging your phone while on the road could use up your car's battery, too. If your engine is off, but you still use the radio—the phone will draw power from your car's battery as it charges. This usually isn't a big deal for those who own new cars with healthy batteries Nichols says. But if your car is an older model, you might want to avoid charging your phone through its USB port.

    Most importantly, it, s not safe to use your phone while operating a vehicle. “Anytime a person's hands leave the wheel or eyes leave the road, it becomes very dangerous for them and the other people around them,” Nichols says. Bottom line: Play it safe, and wait until you get home to plug in.

Three magical destinations just one day!

    TOUR DETAILS

    Windsor Castle

    Time-honored in history, Windsor Castle is proudly located on a wooded hill overlooking the Thames River. Dating back to Norman times, it is famous for sweeping landscaped gardens, which is easy to see why it's the Queen's favorite week place. Famous for its architecture and Royal palace, the Castle was built in the 11th century after the Norman invasion. It's home to priceless artworks and you can visit Queen Mary's Dolls' House. Remember don't miss the ceremony—Changing of the Guards.

    Stonehenge

    Stonehenge is located in the county of Wiltshire. This is your chance to see a side of the world-famous stones that most people don't get a chance to see! You will never forget your first glimpse of grand Stonehenge with its rocks rising up against the skyline on Salisbury Plain. There are many unsolved mysteries about the rocks. Was Stonehenge intended as a religious temple? A clock for astronomy? A burial ground? Make up your own mind as you explore this unique site that has confused the world for 5, 000 years.

    Bath

    Beautiful Bath was the first city in England to be added to the UNESCO World Heritage List. No tour of Bath would be complete with a visit to the famous Roman Baths that gave the city its name. This beautifully preserved bathing site still has flowing water from Brain's only hot spring. You will be amazed by the impressive torch-lighting ceremony as dusk falls. You can also have a taste of Bath's water in Pump Room, where hot waters are drawn for drinking.

German cities are redrawing road markings to create new cycle paths for the duration of the Covid-19 lockdown, as cyclists demand more space to physically distance on their way to work.

Local authorities in the Kreuzberg district of Berlin trialled (试行) temporary widening of two cycle paths on 27 March, arguing it would help cyclists keep the required 1.5-metre distance apart while car traffic was down owing to Germans' coronavirus (冠状病毒) restrictions.

On Friday, the council declared the plan a success because it had improved cycling safety while not blocking traffic.

The council said it had used removable tape and mobile signs to mark out the widened paths, which can be removed when the current restrictions on movement are lifted.

Residents in 133 other German cities have formally submitted applications for similar pop-up bike paths to their local authorities on the back of a campaign by Environmental Action Germany (DUH), an environmental NGO.

The campaign group cites new research linking air pollution to higher coronavirus death rates as an argument for redrawing road signs across the country. "The coronavirus is showing us that clean air is necessary," said DUH's chair, Jurgen Resch. "It is now especially important to temporarily make it more important for people to move safely on their bikes. This will help improve air quality, enable exercise in fresh air while keeping a safe distance and avoid unnecessary accidents."

In Germany, bike repair shops are allowed to work because of the Covid-19 going on. Three federal states, Berlin, Saxony-Anhalt and Mecklenburg-Vorpommern, have allowed bike shops to stay open.