On 29 May last year, I was doing my swim training for a half Ironman race in the bay near my home.

    I was finishing my first loop (圈) when I felt jaws coming around my body and a sharp pain. The water was dark, so I couldn't see anything. It just came out of nowhere and then it was gone in a flash. I knew it was something really big and assumed it was a shark. I panicked, but knew I needed to get out of the water. I was kicking wildly in case it came back. There was a lifeguard boat close by, so I waved my arms in the air and screamed for help. It got to me within 20 seconds. At that point I didn't feel anything; adrenaline (肾上腺素) had taken over. The lifeguards held me under the arms and pulled me up out of the water. Then the pain kicked in and it was pretty hard to bear. Some muscle had been bitten off my right arm. I felt a lot of warm, gushing blood.

    My chest felt heavy, as if someone had put their foot on it, and I was having trouble breathing. It was extremely painful. When I got to the hospital, I told the nurses to put me to sleep because of the pain. I just wanted them to fix me.

    I woke up after surgery four hours later. My doctor was amazed when I managed to move my fingers: the bite just missed a major nerve. My right lung had been damaged; I had several broken bones and a nerve in my leg was cut, so I have reduced feeling at the top of my leg. The shark also bit through my upper back muscle.

    Local experts determined that the shark was probably 9-10 feet long. It was young, about seven years old. It just attacked me, left and didn't come back because it figured I wasn't food.

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

    Have you ever lost your direction? Then you might find satellite navigation(satnav) systems(卫星定位系统) helpful.

    A satnav system uses groups of satellites. They send information to a receiver(接收器), such as your smartphone. Then they can find where you are.

The earliest satnav system is the Global Positioning System(GPS) of the United States. The US has put 24 satellites into space to make sure GPS can locate(定位) a person correctly and globally. Likewise, Russia's GLONASS and European Union's Galileo can also work globally.

    But China is catching up, building its own BeiDou Navigation Satellite System. BeiDou is China's homegrown satnav system, reported Xinhua. It was set up in 2000, when China sent BeiDou's first navigation experiment satellite into space. With it, China became the third country to build a satnav system after the US and Russia.

    BeiDou can find you wherever you are. It helps you go faster by finding shortcuts(捷径) and using correct directions. When you are in trouble and call the police, they will know exactly where you are if you have a cellphone that uses BeiDou.

    Today, there are more than 20 BeiDou satellites above our heads. And the system is able to offer open services to the Asia-Pacific region(亚太地区).

    In November, China plans to send more BeiDou-3 satellites into space. BeiDou-3's position accuracy(准确度) is less than five meters, Ran Chengqi, a senior designer of the satellite navigation system, told China Daily.

    By 2020, BeiDou is planned to have 35 satellites and begin serving globally, reported Xinhua.

    Does your local high school have a student newspaper? Only 1 in 8 of New York's public high schools has student newspapers – and many of those are published just a few times a year. A few more are online, which can leave out poorer schools.

    Rebecca Dwarka, an 18-year-old senior who works for her student paper said, “Facebook is the new way of finding out what happened. Nobody wants to actually sit down and read a whole article about it. This makes a 'whole article' sound a little like a long sentence in lonely places.”

    I am not nostalgic(怀旧的) about high school student newspapers and never worked for mine. I put out what was then called a personal magazine with a group of friends because we wanted to write about peace, war and rock 'n' roll without school officials warning us not to make jokes about the local officials.

    School newspapers are in decline(衰落) because students now find out what happened on social networking websites. This is a little discouraging because it proves that for millions of Americans, journalism is becoming a do-it-yourself thing. Every citizen can be a reporter.

    When something happens, we look for social media messages. Facebook posts and Tweets have become the means by which citizens and reporters can prove, deny, pass on stories and express opinions without the press' challenging, researching or slowing the message.

    But truly good journalism is a craft, not just a blog post. It requires seeing something carefully and it uses an eye for details to help prove a larger view. And even journalism that conveys an opinion tries to be fair. If school newspapers begin to disappear, I hope there are other ways for students to learn that.

    Some people say summer is the time when teachers should get more pay. But not everyone is grateful to teachers for keeping kids occupied (无空闲的) between August and June: Washington state representative Liz Pike has written a Facebook post, titled "A life in the day of a WA state representative," and responded to teachers' complaints of rising costs of living. The post has received criticism for being anti-teacher. After reading her post, I feel that Liz Pike should rethink her criticism of public school teaching and avoid comparing it to the private school.

    Many of us teachers would certainly like teaching to be more like the private school. We see nothing wrong with fair pay for fair performance. In fact, performance is the name of the game. With standardized testing popular throughout K-12 education, teachers are some of the most analyzed and performance-measured employees in the United States. Liz Pike is very angry that teachers want raises even while test scores are dropping. Well, how are we supposed to have discipline (纪律) in the classroom when our hands are tied and we can hardly do anything with naughty students or fail students who are not prepared to move on to the next grade?

    Teachers would love to be able to turn education around and improve student performance. But we can't, and we should not suffer for it. Unlike private school businesses, public schools cannot turn away "customers". A private school business serves customers who walk through the door of their own free will, while public schools have to educate students who only attend because courts say they must.

    She says those who are "uninspired" by a lack of a cost of living increase should give up teaching. Is this the message that she thinks should be sent to the students whose academic performance she claims (声称) to care so much about? That "if you love it you'll shut up and not stand up for yourself"? I think teachers should stand up for themselves and I also think supporting teachers can make teachers teach children how to stand up for themselves.

Foldable phones are once again facing questions about their durability(耐久性).The Galaxy Z Flip and the Motorola Razr are now both available to buy in the US-but early reports suggest the screens are easily damaged.

One media published photos of two layers of the Razr's display separating, affecting the touch screen. The Galaxy flip, meanwhile, boasts(自夸)a "flexible glass" display—but tests appear to show it scratching(刮擦)as easily as plastic.

In a statement, Samsung said the display had a protective layer, and had undergone extensive testing. "While the display does bend, it should be handled with care, "it said.

The Z Flip's "pretty thin glass" is one of Samsung's primary marketing messages for the new phone. But a durability test conducted by popular Zack Nelson, a regular buyer, suggested it was no more durable than soft plastic screen, and could even be dented(痕)by fingernail.

Nelson said Samsung's screen scratched exactly how plastic screen would react. "I don't know what material this is, but Samsung definitely shouldn't be calling it glass," he said. He found that the screen of the Motorola Razr scratched as easily but it is not marketed as "glass".

The Motorola Razr was put on sale 13 days ago in the US, but Raymond Wong, an editor says the flexible screen on his handset has already broken. The upper layer of the Razr's screen separated from the bottom, creating "a giant horizontal air bubble" for no apparent reason. He wrote that the fault appeared after 45-minute train ride during which the phone was in his pocket. The screen was completely warped from hinge-to-hinge with the top layer raised like a poorly applied screen protector. But Mr. Wong said that apart from the visual problem, the damage has affected the responsiveness of the touchscreen.

Although a few recreational snowmobilers (驾驶摩托雪橇者) destroy ecosystems as they ride through the wilderness, most snowmobilers love and respect America's natural heritage. That's why they brave the cold to explore what is left of wild America — including Yellowstone National Park. Unfortunately these snowmobilers are unconsciously damaging what they love. Because snowmobiles in the park not only create both air and noise pollution but also strains (使紧张) the already tight budget of the park service, recreational snowmobiles should be banned from Yellowstone National Park.

It may be hard to imagine that about 1,000 snowmobiles a day could lead to air pollution in a park half the size of Connecticut, but in fact they can. In addition to polluting the air, snowmobiles are noisy, disturbing the peace and silence that park visitors have a right to expect. One study reports that twelve snowmobiles traveling together could be heard as far as two miles away. Such noise affects the park's wildlife.

Funds that should be used to preserve Yellowstone National Park and its wildlife have been used to deal with the snowmobile issue. Also, park rangers are spending an increasing amount of their valuable time policing snowmobilers, which takes away from park rangers' primary responsibility—preserving this country's treasured natural resources.

Opponents of a ban argue that a central mission of the park service is to provide access to national parks. Admittedly, winter access is important, but ordinary people can enjoy the park by means other than snowmobiles. Also, the park service's mission is not just to provide access to the parks; no less important is its mission to preserve the parks' pristine natural resources for future generations.

Even with a ban on snowmobiling in the park itself, the Yellowstone area would still earn the title of Snowmobiling Capital of America. All of the streets of West Yellowstone, the area's major town, are open to snowmobilers, and many trails run out of the town. As to Yellowstone National Park, a ban on snowmobiles would allow the park service to devote more of its limited resources to one of its primary missions: the protection of natural resources. Visitors would still be able to appreciate Yellowstone's beauty— its geysers, its wildlife, and its snow-covered vistas —throughout the park's long winter.