Earthquakes usually happen on the edges of large sections of the Earth's plates. These plates slowly move over a long period of time. Sometimes the edges, which are called fault lines, can get stuck, but the plates keep moving. Pressure slowly starts to build up where the edges are stuck and, once the pressure gets strong enough, the plates will suddenly move causing an earthquake.

Generally, before and after a large earthquake there will be smaller earthquakes. The ones that happen before are called foreshocks. The ones that happen after are called aftershocks. Scientists don't really know if an earthquake is a foreshock until the bigger earthquake occurs.

Shock waves from an earthquake that travel through the ground are called seismic waves (地震波). They are most powerful at the center of the earthquake, but they travel through much of the earth and back to the surface. They move quickly at 20 times the speed of sound.

Scientists use seismic waves to measure how big an earthquake is. They use a device called a seismograph to measure the size of the waves. The size of the waves is called the magnitude.

To tell the strength of an earthquake scientists use a scale called the Moment Magnitude Scale or MMS (it used to be called the Richter scale). The larger the number on the MMS scale, the larger the earthquake. You usually won't even notice an earthquake unless it measures at least a 3 on the MMS scale. Here are some examples of what may happen depending on the scale:

4. 0— Could shake your house as if a large truck were passing close by. Some people may not notice.

5. 0—If you are in a car, it may shake. Glasses and dishes may rattle. Windows may break.

6. 0— Items will fall off shelves. Walls in some houses may crack and windows break. Pretty much everyone near the center will feel this one.

7. 0— Weaker buildings will collapse and cracks will occur in bridges and on the street.

8. 0— Many buildings and bridges fall down. Large cracks in the earth.

9. 0 and up— Whole cities flattened and large-scale damage.

    What is the greatest threat to mankind? Maybe different people come up with different answers. However, there is no denying the fact that the only threat to humankind, apart from humankind itself, is, without any doubt, the nature. Natural disasters are the result of natural environmental processes that have a damaging effect on people. Natural disasters can come in many forms: such as geological events like earthquakes, tsunamis or mud-rock flows, climatic events like storms, hurricanes or tornadoes and fire events like forest fires and wildfires.

    The damage done by natural disasters is mainly as a result of our inability to predict(预测) exactly when they will happen. Although great progress has been made in designing and developing forecasting models for some natural disasters, complete certainty is still impossible. Even to be pessimistic, there is a possibility that human beings will never achieve accurate prediction of the happening of all natural disasters.

    What's more, even though we were able to predict these disasters from nature, preventing them is equally impossible. So we only have two ways to both prevent injuries or deaths and reduce economic losses to the least. These two methods are to prepare before a natural disaster comes to hit, and to manage the necessary resources and public services after a natural disaster strikes.

    These two things have always been at the leading position of the projects of both national governments and international organizations. In the United States, the Federal Emergency Management Agency is responsible for the "preparedness, response and recovery planning" of both man-made and natural disasters.

    Most natural disasters cannot be prevented, and both emergency preparation and good disaster management are the best ways to deal with them. Although natural events may appear to serve no purpose but simply to punish and destroy, natural disasters, a perfect symbol of the great power of the nature, are display of our planet's evolution and its state of change.

Shop with Your Doc is part of a broader and still growing movement in US medicine to shift the focus away from simply treating disease toward caring for the whole person. It is meant to help people make educated, healthy choices, one grocery cart at a time. Across the country, hospitals are setting up food banks and medical schools are putting cooking classes on the curriculum. Nonprofits are connecting medical centers with community resources to ensure that low-income Americans have access to fresh fruits and vegetables.

For centuries, Western medicine's mission was to cure disease. "But over the past generation, two significant trends are of concern to the medical community, "says Timothy Harlan, executive director of Goldring Center for Culinary Medicine at Tulane University in New Orleans. Healthcare costs began to increase sharply, and relatively inexpensive, poor-quality food became more common. "There's a very straightforward link between people improving their diets and improving the condition that they have, "Dr·Harlan says.

The connection drove the medical and nonprofit communities to rethink their approach 10 health. What emerged(浮现)was the concept of the" social determinants of health"-the concept of taking into account the biological, physical, and socioeconomic circumstances surrounding a patient. A healthy person isn't just someone who is free from disease, the theory goes；he or she also enjoys" a state of complete mental, physical and social well-being. "

The question the medical community now faces is how to get patients-especially low-income families-to recognize these determinants and make it possible for them to eat and live healthier. In Boston, medical experts responded by creating an on-site pantry(食品室)at Boston Medical Center. Since its founding in 2002, the pantry has evolved into a kind of nutrition center when primary care providers at BMC send patients food. Today the pantry, which gets 95 percent of its stock from the Greater Boston Food bank, hosts free cooking classes and serves about 7, 000 people a month. The Greater Boston Food Bank has also launched its own initiatives(倡议), striking partnerships with four community health centers across the state to offer free mobile produce markets. The organization also helped develop toolkits(软件包)that map local pantries, markets that accept government food vouchers(代金券), and other resources.

At Tulane in New Orleans, Harlan is leading the development of a curriculum that combines medicine with the art of food preparation. His philosophy: Doctors who know their way around a kitchen are better at helping their patients. And empowering(增强自主权) patients to take charge of their own diets is one way to help them deal with the incredible costs of health care, Harlan says. The curriculum has since been adopted at 35 medical schools around the United States. "Chipping away at bad habits is a good place to start getting patients to think about the choices they make for themselves and their families, "says Dr Maureen Villasenor, the Orange County pediatrician(儿科医生).

    In 1987, a mountain on Mercury (水星) got a name--Li Qingzhao, the name of a Chinese female poet. According to the International Astronomical Union, all new mountains on Mercury must be named after a litterateur (文人) or an artist who was famous for more than fifty years, and dead for more than three years, before the date they are named. Of the total of 310 names, fifteen are named after famous Chinese writers and artists, and Li Qingzhao is one of them, together with Li Bai, Bai Juyi ,Cao Xueqin and Lu Xun.

    What did Li Qingzhao do to deserve such an honour? Li is a poet of the Song Dynasty. Compared with other male poets in China, who have left hundreds or even thousands of poems, Li has only eighty-seven, like a drop in a bucket of water However, her talents and artistic creativity as shown in her eighty-seven works have earned her a lasting place in the Chinese literary circle.

    Li was born into a scholar-official family in 1084. Like other young women in a rich family, she was well-read and trained in Chinese calligraphy (书法) and musical instrument. Most young women of rich families were taught to follow the "Three Obediences and Four Virtues" at that time, while Li was free in both character building and artistic development.

    When it was time for her to start another stage in life--marriage, Li married Zhao Mingcheng. a student at the supreme academy of the imperial court. The couple devoted their spare time to their common interests --literature and the collection of calligraphy and painting.

    Unluckily, their happiness didn't last long. The power struggle at the very top of the government destroyed everything. Li first followed her husband to Qing Zhou, and spent the next ten years there. It turned out that the ten years in Qing Zhou was the most productive period for her artistic creativity. Then in 1127, when the North Song Dynasty ended, Li followed her husband to Lin'an. Soon her husband died. And the worst part was that not only did she lose her loved husband but she also lost most of her accumulated (积累的) works.

    Later, Li remarried a government official, who turned out to be a total liar and treated her badly. She died in 1155 in loneliness and pain.

—It's true. Many university classes are taught in English ______ the native language is not English.

Every year, Time magazine picks out what it calls "The 25 Best Inventions" of the year. Here, Teens has chosen some of the most interesting ones.

Ember Mug

It's hard to always keep coffee at the right temperature, especially in winter. It's too hot to drink at first, but before we know it, it gets too cold and loses all its taste. The perfect level of warmth for a cup of coffee only lasts for 37 seconds, which makes the Ember Mug a great invention. It keeps your coffee or tea at a certain temperature, anywhere between 45℃ and 62℃, once you set it through a smartphone app.

Tasty One Top

TV cooking shows make cooking look so easy, but it's almost impossible to get the recipes to cook the same as how the professionals cook. However, the Tasty One Top DIY cooking companion is here to help. Developed by BuzzFeed, the cooker can be connected to a smartphone app, which has more than 1, 700 recipes and videos. You choose a recipe and the app will let the cooker know what to do. For example, it'll tell you when to turn your steak or when to add certain ingredients.

Jibo

Smart speakers from companies like Amazon and Xiaomi have added a lot of fun to our lives, but they're still just faceless speakers. However, Jibo, developed by MIT professor Cynthia Breazeal, has brought smart technology to life. Said to be "the world's first social robot for the home", Jibo looks like a cartoon character. Inside its "head", there are various sensors and cameras, which allow it to recognize faces and speech. It can also set alarms, remind you of important things, tell you the weather and read news or messages from your friends and family.

While in an emergency, he is always   .

WELCOME AND ARRIVAL INFORMATION

    Welcome to Harvard University Housing and thank you for choosing to live with us. To help you make a smooth transition please read the information below on panning your arrival.

    Pets

    Dogs living with you in your pet-friendly apartment must be vaccinated(接种疫苗) for rabies and licensed with the City of Cambridge every year.

    International Students

    Consider unlocking your phone prior to leaving your home county. This will enable you to use a SIM card from a company such as campus SIMS or US Mobile in your phone after you arrive. Those SIM cards may be available at the Property Management Office.

    Driving

    If you plan on bringing a moving van or truck it will not fit under the overpasses(天桥) on Soldiers Field Road and Memorial Drive. Plan your route in advance to avoid a risky and costly problem.

    Parking arrangements for trucks and vans must be made in advance as well. Visit your property page for information about parking your car.

    Furniture and Lighting

    Most HUH units have no furniture-the unit is empty except for a stove and a refrigerator. You need to bring, buy, or rent a bed, other furniture, and household items. In many HUH units, rooms do not have overhead lights, so you also may need table or floor lamps.

    If you want to stock up on groceries and some household items as soon as you arrive, please find information about "Grocery Shopping" by clicking the drop-down menu.

    Two weeks earlier, my son, Ben, had got in touch. He'd moved to England with his mum when he was three and it had been 13 years since I'd 1 seen him. So imagine my 2 when he emailed me saying he wanted to come to visit me.

    I was 3 ! I arrived early at Byron Bay where we were supposed to 4 . The bay was5 in sunshine, and there was a group of kayakers around 150m off the shore. Getting a little 6 .I realized one kayak（皮划艇）was in 7 . "Something's not 8 !" I took off my T-shirt and 9 into the water. I saw there were two instructors on board and a man lying across the middle. He was 10 violently. Linking arms with one of the instructors. I helped 11 the young man out of the water. He was unconscious and as I looked at his face, something 12 to me. Those brown eyes were very 13 . "What's his name?" I asked the instructor. "Ben," he replied, and immediately I 14 . That stranger was my son!

    The instructors called for an ambulance. 15, after a brief stay in hospital. Ben was well enough to be allowed to 16 and later the family met up for dinner. We chatted about everything and then Ben 17 to me. "I'm just want to say thank you," he said, "You 18 my life!"

    I still can't believe what a 19 it was. I'm just so glad I was there 20 to help my son.

    In many countries, schools have long summer holidays, with shorter holidays in between. However, a new report suggests shortening school holidays to stop children forgetting what they have learnt during the long summer break. Instead of three school terms, it says, there should be five eight-week terms. And there should be just four weeks off in the summer, with a two-week break between the other terms.

    Sonia Montero has two children at primary school and works full-time. She supports the idea. “The kids,” she says, “have much longer holidays than me and I can't afford to take several weeks off work, so I need someone to take care of them. But nobody wants the work in the summer months — they all have holidays of their own.”

    Not surprisingly, some young people disagree. Student Jason Panos says “It's a stupid idea. I would hate staying at school in the summer. It's unfair, too. The people who suggest this had long school holidays when they were young, but now they want to stop us enjoying the summer. The kids in Spain and America have much longer holidays than here, but they don't forget everything they've learnt in a few months.”

    Nadia Salib agrees. “Sure,” she says, “the first week at school after the summer is never easy, but you soon get back into it. The real problem round here is that kids get bored after so many weeks out of school, and then some of them start causing trouble. But the answer is to give them something to do, not make everyone stay in school longer.”