“I see you've got a bit of water on your coat,” said the man at the petrol station. “Is it raining out there?”“No, it's pretty nice,” I replied, checking my sleeve. “Oh, right. A pony(马驹) bit me earlier.”
        As it happened, the bite was virtually painless: more the kind of small bite you might get from a naughty child. The pony responsible was queuing up for some ice cream in the car park near Haytor, and perhaps thought I'd jumped in ahead of him.
        The reason why the ponies here are naughty is that Haytor is a tourist-heavy area and tourists are constantly feeding the ponies foods, despite sighs asking them not to. By feeding the ponies, tourists increase the risk of them getting hit by a car, and make them harder to gather during the area's annual pony drift(迁移).
        The purpose of a pony drift is to gather them up so their health can be checked, the baby ones can be stooped from feeding on their mother's milk, and those who've gone beyond their limited area can be returned to their correct area. Some of them are also later sold, in order to limit the number of ponies according to the rules set by Natural England.
        Three weeks ago, I witnessed a small near-disaster a few mils west of here. While walking, I noticed a pony roll over on his back.       “Hello!” I said to him, assuming he was j  ust rolling for fun, but he was very still and, as I got closer, I saw him kicking his legs in the air and breathing heavily. I began to properly worry about him. Fortunately, I managed to get in touch with a Dartmoor's Livestock Protection officer and send her a photo. The officer immediately sent a local farmer out to check on the pony. The pony had actually been trapped between two rocks. The farmer freed him, and he began to run happily around again.
      Dartmoor has 1,000 or so ponies, who play a critical role in creating the diversity of species in this area. Many people are working hard to preserve these ponies, and trying to come up with plans to find a sustainable(可持续的) future for one of Dartmoor's most financially-troubled elements.

    In London's art gallery six or seven men, mostly in their 30s, are busy painting the walls with new designs in colorful lettering and clever tricks. Tins of spray paint and beer stand on the ground. The atmosphere is not unlike that of a golf course: a mix of concentration and relaxation.

    Graffiti(涂鸦) painting is traditionally a daring hobby. Teenagers avoid security guards to put their names on trains and buses. But over the past decade that has almost disappeared from Britain's cities. Between 2007 and 2017 the number of incidents of graffiti recorded by the British Transport Police fell by 63%. A survey by the environment ministry shows that fewer places are damaged by tags(绘名) than ever. Graffiti are increasingly limited to only a few walls. In time the practice may die out entirely.

    The most obvious reason for the decline in tagging and train-painting is better policing, says Keegan Webb, who runs The London Vandal, a graffiti blog (博客). Numerous cameras mean it is harder to get away with painting illegally. And punishments are more severe. A generational change is apparent, too. Now teenagers prefer to play with iPads and video games. Those who do get involved tend to prefer street art to graffiti. And the internet helps painters win far more attention by posting pictures online than they can by breaking into a railway yard.

    Taggers and graffiti artists mostly grew up in the 1980s and 1990s. Those men are now older and less willing to take risks. "We can't run away from the police any more," says Ben Eine, who turned from tagging to street art. The hip-hop culture that inspired graffiti in the first place has faded. Video games and comic books provide more inspiration than music.

    Graffiti may eventually disappear. But for now the hobby is almost respectable. Mr Eine says he has lots of friends who used to paint trains. Now with wives and children, they paint abandoned houses at the weekend. It has become something to do on a Sunday afternoon—a slightly healthier alternative to sitting watching the football.

    The most widespread fallacy (谬论)of all is that colds ire caused by cold. They are actually caused by viruses passing on from person to person. You catch a cold by coining into contact, directly or indirectly, with someone who already has one. If cold causes colds, it would be reasonable to expect the Eskimos to suffer from them forever. But they do not. And in the isolated Arctic Regions explorers have reported being free from colds until coming into contact again with infected people from the outside world by way of packages and mail dropped from airplanes.

    During the First World War soldiers who spent long periods in the trenches(战壕), cold and wet, showed no increased tendency to catch colds.

    In the Second World War prisoners at the Auschwitz concentration camp，naked and starving, were astonished to find that they seldom had colds. At the Common Cold Research Unit in England, volunteers took part in experiments in which they gave themselves to the discomforts of being cold and wet for long stretches of time. After taking hot baths, they put on bathing suits, allowed themselves to be with cold water, and then stood about dripping wet in drafty rooms. Some wore wet socks all day while others exercised in the rain until close to exhaustion. Not one of the volunteers came down with a cold unless a cold virus was actually dropped in his nose.

    If then, cold and wet have nothing to do with catching colds, why are they more frequent in the winter. Despite the most pains-taking research, no one has yet found the answer. One explanation offered by scientists is that people tend to stay together indoors more in cold weather than at other times, and this makes it easier for cold viruses to be passed on.

    City College

    ADMISSION REQUIREMENTS

    All high school graduates and anyone 18 years of age or older, with or without a high school diploma, are suitable for admission. Individuals under the age of 18 who possess a high school diploma are also suitable for admission.

    HOW TO ENROLL IN CREDIT COURSES

    New and readmitted students must complete and hand in a credit admissions application form available online at www.ccsf.edu.

    BEFORE YOU REGISTER:

    Learn about your skill level in English and Math through our assessment service;

    Attend an orientation (新生报到会) to hear about support services

    Meet with a counselor (adviser) to select your courses;

    Find out if you are required for attending the entrance examinations.

    HOW TO ENROLL IN NONCREDIT COURSES

    Courses in Noncredit Programs are free of charge (no enrollment fee). For information on how to enroll in noncredit courses, click here.

    PARKING

    Students, faculty and staff are encouraged to use public transit. Click here for Parking Regulations.

    SERVICES

    City College services include a bookstore, cafeteria, health center, tutoring center, career and transfer center, counseling, financial aid, library, learning resource center, student government offices, campus police, disabled students programs and more.

    March 21 has been declared World Sleep Day, a time to recognize and celebrate the value of sleep. Many sleep experts hope it will be a wake-up call.

    According to a 2016 poll（民意调查）by the National Sleep Foundation, nearly 4 in 5 Americans don't get as much sleep as they should during the workweek. On average, adults are thought to need at least eight hours of sleep a night, although some can manage with less and some won't do well without more. But the survey found that, on workdays, only 21% of Americans actually get a full eight hours of sleep, and another 21% get less than six.

    To many of us, the thought of spending more time sleeping is, well, a big yawn. On the other hand, the thought of being smarter, thinner, healthier and more cheerful has a certain appeal. And those are just a few of the advantages that can be ours if we consistently get enough sleep,  researchers say. Also on the plus side： We're likely to have better skin, better memories, better judgment, and, oh, yes, longer lives.

    "When you lose even one hour of sleep for any reason, it influences your performance the next day, " says Dr. Alon Avidan, director of the UCLA Sleep Disorders Center.

    A study published last year found the same to be true even of children.  When kids aged 8 to 12 slept for just one hour less for four nights, they didn't function as well during the day.

    But sleeping has an image problem. "We see napping or sleeping as lazy, " says Jennifer Vriend, a clinical psychologist in Ottawa, Canada, and the leading author of the study with children. "We put so much emphasis on diet, nutrition and exercise. Sleep is in the back seat. " In fact, she adds, no matter how much we work out, no matter how well we eat, we can't be in top physical shape unless we also get plenty of sleep.

    Living in the wild can be hard. Finding food and staying safe aren't easy. Each day, animals try to survive in their habitats. Not all animals get by on their own. Some animals form a close partnership with other kinds of animals. These pairings are called symbiotic(共生的)relationships.

    In a symbiotic relationship, the animals depend on each other. One animal helps the other meet its needs. Sounds good, right? Not always. Some animals are not very kind to their partners. In some cases, one animal meets its needs but hurts its partner. Take ticks(扁虱), for example. These insects suck blood to live. To get blood, they attach themselves to other kinds of animals. Ticks can pass germs(细菌)that cause disease instead of helping their hosts.

    In other relationships, animals don't treat their partners so poorly. Both animals benefit from living with the other animal.

    Small animals called cleaner shrimps(清洁虾)have found a way of helping fish. As their name suggests, the shrimps clean the fish. They hang out at what scientists call a cleaning station. A fish stops by. Then a shrimp climbs onto the fish and even steps into the fish's mouth. The shrimp uses its tiny claws to pick stuff off the fish's body. That can include dead skin and tiny pieces of food that can hurt the fish. The fish gets a nice cleaning. The shrimp enjoys a tasty meal of fish trash.

    Small birds called plovers(灰斑)are also in the cleaning business. They have big customers-crocodiles. Crocodiles have long noses filled with sharp teeth. Cleaning them is funny. When a crocodile opens its mouth, the plover hops right in. It lets the plover eat small, harmful animals attached to the crocodile's teeth. The plover gets an easy meal while the crocodile gets clean teeth.