A new international study shows that some people's biological clock plays a powerful role for their life expectancy, regardless of lifestyle choices.

    Published in the latest issue of Aging on Wednesday, the study has found the most definitive evidence to explain why some people keep healthy lifestyle but die younger than others.

    Geneticist Steve Horvath from the University of California, Los Angeles (UCLA), led a team of 65 scientists around the world to record age-related changes to human DNA, analyse blood samples collected from 13, 000 people and estimate their lifespan.

    A higher biological age, regardless of actual age, consistently predicts an earlier death, the study says.

    "You get people who are vegan, sleep 10 hours a day, have a low-stress job, and still end up dying young," Horvath said in a statement. "We have shown some people have a faster innate aging rate."

    The findings discovered that 5 percent of the population ages at a faster biological rate, which translated to a roughly 50 percent higher than average risk of death at any age.

    "The great hope is that we find anti-aging interventions that would slow your innate aging rate," Horvath said, adding that "this is an important milestone to realizing this dream."

Best Travel Guides by Continent

     We've broken down(分类)the best travel guides, by continent, to help you find student discounts and travel like a local on your next adventure.

Europe—Let's Go Europe 2017: The Student Travel Guide

     Let's Go was founded about 55 years ago when a Harvard student had an idea to provide accessible, budget travel lips for young people. Students lave its amusing pages. Let's Go Europe 2017 has everything you need for your trip—from the best beer in Brussels to how to avoid the lines at the Louvre.

Africa—The Rough Guide to Cape Toxin, the Winelands, and the Garden Route

     With its colorful photos and detailed tips on how to make the most of South Africa, The Rough Guide is the book to gel when visiting Africa. You may not have access to Google Maps when you1 re out exploring but that's OK. The Rough Guide also comes with easy use to maps.

     It can be purchased as an eBook, or as a paperback(平装本).

Asia—Lonely Planet: South-East Asia on a Shoestring

     This guide is perfect for those backpacking through the hidden treasures of South-Ea.sl Asia. With detailed recommendations from experts in the area, this guide helps first-timers as well as experienced backpackers. This book can lie purchased as a paperback travel guide. A download for an eBook or separate chapters can be purchased to serve as a guide to specific cities.

North America—Planet USA Travel Guide

     With detailed reviews of the best places to eat, sleep, and explore, Lonely Planet is linked with budget-friendly attractions and that's why it makes our best travel guides list. This travel guide is available in paperback.

    Jayson McCarthy, 12, was born without fingers on his left hand. That didn't stop him from being able to do many tasks. But Jayson could not grasp more than one object at a time. So Jayson 's father, Paul, created a Prosthesis(假肢), using a 3D printer. Now Jayson has fingers that open and close. “It was a do－it－yourself, father－and－son adventure，” says Paul.

    When Jayson was a baby, his doctor advised his parents not to give him a prosthetic hand until he was in his early teens. “The doctor said Jayson should first learn to get full use out of the hand he was born with，” says Paul. As Jayson got older, his father looked into purchasing a prosthetic hand, which can cost as much as $30，000. Paul found a more affordable solution.

    One day, Paul discovered a video on the Internet about Robohand, a prosthesis created with a 3D printer. He downloaded the free instructions and called Robohand's creators for advice. They told him all he needed was a 3D printer—which costs around $2，000—and some materials.

    Luckily, Jayson 's school had recently purchased a 3D printer and it offered to help Paul build the hand for Jayson n. “We used a soccer shinguard(护胫), cardboard(硬纸板), and tape. They cost about $10，” says paul.

    With his new hand, Jayson can do things better. “I can help my mom more, because now I can carry two grocery bags，” he says.

    Jayson 's father has already built several hands for Jayson. Jayson helps design each one. He says there's one thing in particular that he wants to do with a future prosthesis. “The goal，” he says, “is to be able to tie my shoelaces(鞋带)．”

    Spring and fall are usually thought to be enjoyable seasons. However, it is not always the case. {#blank#}1{#/blank#} It makes people suffer a lot from it.Why can't they find a cure（疗法）for the common cold?The answer is easy. There are actually hundreds of kinds of cold viruses（病毒） out there. You never know which one you will get.{#blank#}2{#/blank#}

    When a virus attacks your body, your body works hard to get rid of it.{#blank#}3{#/blank#} .You feel terrible because you can't breathe well, but your body is actually eating the virus.Your temperature goes up and you get a fever, but the heat of your body is killing the virus.You also have a runny nose to stop the virus from getting into your cells.You may feel very uncomfortable, but actually your wonderful body is doing everything it can to kill the cold.

    {#blank#}4{#/blank#}.In China and some other countries, for example, some people might eat chicken soup to make themselves feel better. Some people take hot baths and drink warm liquids. Other people take medicine to stop various symptoms（症状）of colds.

There is one interesting thing to note-some scientists say taking medicine when you have a cold is actually bad for you. The virus stays in your body longer because your body doesn't have a way to fight it and kill it. {#blank#}5{#/blank#}.There is a joke, however, on taking medicine when you have a cold.It goes like this: It takes about one week to get over a cold if you don't take medicine, but it takes only seven days to get over a cold if you take medicine. So you should trust the function of your body.

    We've talked about snails（蜗牛）and their slow move.But much of the time snails don't move at all.They're in their shells（壳）—sleeping.

    Hot sun will dry out a snail's body.So at the least sign of hot sun,a snail draws its body into its shell and closes the opening with a thin cover.Then it goes to sleep.A snail will die in a heavy rain.So whenever it rains,it goes inside its shell house and goes to sleep.A snail can sleep for as long as it needs to.It can take a short sleep.Or it can sleep for days at a time.And it spends all the winter months in its shell,asleep.

    the shell.When hungry,the snail looks for food.It can't see very well.Its eyes,at the ends of the top feelers（触角）are very weak.But its sense of smell is very strong.It helps the snail to the new greens.Then the snail's little mouth goes to work.

    A snail's mouth is no longer than the point of a pin（针）.Yet it has 256,000 teeth!The teeth are so small that you can't see them.But they do their work.If you put a snail in a hard paper box,it will eat its way out.And if a snail wears out its teeth,it will grow new ones.

    Mostly,a snail looks for food at night.But on cloudy days it eats in the day time.It cats all day long.A snail can go on eating for hours and never feel full.

    Renowned British physicist Stephen Hawking died peacefully at his home in the British university city of Cambridge in March 14 at age 76.

    Hawking, whose 1988 book "A Brief History of Time" became an unlikely worldwide bestseller and cemented (奠定) his superstar status, dedicated his life to unlocking the secrets of the Universe. He held the post of Lucasian Professor of Mathematics at the University of Cambridge, which is a position that was once held by Sir Isaac Newton.

    Born in 1942 in Oxford, where his parents spent the final months of pregnancy to avoid the bombings of London, Hawking was said to have been a good student although it wasn't until he was in his 20s that his true potential began to really shine through. Having initially wanted to study Mathematics, Stephen Hawking chose, instead, to read natural sciences with emphasis on Physics.

    Having found University life boring, so much so that he joined the University rowing team to relieve the boredom, it was only following an oral examination that he was awarded a first class degree.

    While at Cambridge, Hawking was diagnosed with a motor neurone (神经元）disease. He was initially given two to three years to live. The illness gradually robbed him of mobility, leaving him confined to a wheelchair, almost completely paralysed and unable to speak except through his trademark voice synthesiser (合成器）.

    Stephen Hawking led an incredible and well documented life. He was referred to in many TV programs, films, and even songs, and appeared as himself in a number of programs including Red Dwarf and the Big Bang Theory. His genius and wit won over fans from far beyond the world of astrophysics (天体物理学）, earning comparisons with Albert Einstein and Sir Isaac Newton.