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Hollywood's theory that machines with evil(邪恶) minds will drive armies of killer robots is just silly. The real problem relates to the possibility that artificial intelligence(AI) may become extremely good at achieving something other than what we really want. In 1960 a well-known mathematician Norbert Wiener, who founded the field of cybernetics（控制论）, put it this way: ＂If we use, to achieve our purposes, a mechanical agency with whose operation we cannot effectively interfere(干预), we had better be quite sure that the purpose put into the machine is the purpose which we really desire. ＂

A machine with a specific purpose has another quality, one that we usually associate with living things: a wish to preserve its own existence. For the machine, this quality is not in-born, nor is it something introduced by humans; it is a logical consequence of the simple fact that the machine cannot achieve its original purpose if it is dead. So if we send out a robot with the single instruction of fetching coffee, it will have a strong desire to secure success by disabling its own off switch or even killing anyone who might interfere with its task. If we are not careful, then, we could face a kind of global chess match against very determined, super intelligent machines whose objectives conflict with our own, with the real world as the chessboard. 

The possibility of entering into and losing such a match should concentrate the minds of computer scientists. Some researchers argue that we can seal the machines inside a kind of firewall, using them to answer difficult questions but never allowing them to affect the real world. Unfortunately, that plan seems unlikely to work: we have yet to invent a firewall that is secure against ordinary humans, let alone super intelligent machines. 

Solving the safety problem well enough to move forward in AI seems to be possible but not easy. There are probably decades in which to plan for the arrival of super intelligent machines. But the problem should not be dismissed out of hand, as it has been by some AI researchers. Some argue that humans and machines can coexist as long as they work in teams—yet that is not possible unless machines share the goals of humans. Others say we can just ＂switch them off＂ as if super intelligent machines are too stupid to think of that possibility. Still others think that super intelligent AI will never happen. 

If you were bringing friends home to visit, you could show them the way. You know the landmarks—a big red house or a bus-stop sign. But what if you were swimming in the middle of the Atlantic Ocean? Could you still find your way home? A loggerhead turtle（海 龟）could. 

According to Dr. Ken Lohmann, loggerheads have a magnetic（磁力的）sense based on Earth's magnetic field. It helps them locate the best spots for finding food and their home beaches. Scientists already know that several other animals, such as whales and honeybees, can detect（探测到）magnetic fields. The difference between them and loggerheads, however, is the way they learn to use their magnetic sense. Young whales and honeybees can learn from adults. Loggerheads are abandoned as eggs.

As newborn loggerheads have no adults to learn from, what helps them figure out how to use their magnetic sense? Lohmann thinks one of the cues was light on the sea. 

Baby loggerheads hatch only at night. However, a small amount of light reflects off the ocean. The light makes that region brighter. Heading toward the light helps them get quickly out to sea, where they can find food. Lohmann tested whether newborn loggerheads use this light source to set their magnetic "compasses"（罗盘）. He and his team put some newborns in a water tank and recorded which way they swam. Around the tank, the scientists created a magnetic field that matched the Earth's. They set a weak light to the east of the magnetic field. Then they let the newborns go.

At first, the newborns swam toward the light. After the scientists turned off the light, the turtles that had seen the light in the east always swam toward east. When the researchers reversed（颠倒）the magnetic field, these turtles turned around and swam toward the new "east".

This and the follow-up experiments all showed that loggerheads use light from the outside world to set their magnetic "compasses" and then remember the "correct" direction. If a turtle hatches on a brightly-lit beach, that would damage its magnetic sense forever and make survival hard for the turtle.

Lohmann's work has led others to protect the habitat of this endangered species. Yet many questions about these creatures remain unanswered, and researchers have a lot to study.

Cathy Brennan calmly paddled her bright yellow kayak（皮艇） down the Potomac River, continuing her voyage, the latest of her solo trips on major waterways. It was tough, but it allowed Brennan to let go of everything else, empty her brain of the everyday chores and focus on the now. "I'm in the moment, looking at the waves. " said Brennan.

The journey is a minimalist style: sleeping bag, small tent, rain jacket, change of clothes, first aid kit, apples and cheese sticks. When she's thirsty, she scoops water from the rivers and pumps it through a filter. "I always drink the river," she says. Brennan loves being on the rivers, seeing the bald eagles above, deer on the banks and a fascinating array of bugs and insects that never find their way into homes.

However, every few days Brennan will find a hotel for the night where she can get a shower and eat a cheeseburger. She'll also check in with her husband John, who has helped her select the river and research the trips at their home. "He's my virtual Sherpa with benefits," Brennan says, laughing. She has a phone with her but rarely calls or texts anyone. Her children usually keep track of her via the transponder that sends them her location every 10minutes or so.

Brennan knows that solo kayaking is not for everyone and she's not reckless. Brennan grew up on a lake and was a strong swimmer and boater from an early age. When going through rough rapids, she watches the weather carefully. She is cautious about where she camps and who is around her. She has packed up her gear and headed back out on the river when she has felt unsafe.

Surely, she is alone on these journeys but she isn't lonely. She suggested that we all need some disconnection from the wired world to find the wider world around us.

The UK is home to 26 world-ranked universities of the top 200 globally. At the heart of each university is the library, a space for students to access resources, absorb knowledge and gather thoughts. Here are some of our must-visit libraries across the UK. 

The British Library, London

Located in London, the British Library is home to over 170 million items. The collections offer a glimpse into literary heritage over the ages, from books to maps to manuscripts. Visitors can browse treasures including Leonardo da Vinci's notebook. Students with a reading pass are known to spend hours at a time in the reading rooms.

Bodleian Old Library, Oxford

Dating back to 1488, the Bodleian Old Library has three notable reading rooms. It is celebrated for its late Gothic architecture. You may recognize the elaborately carved ceiling from scenes in Harry Potter. Students at the university automatically get access to the library. 

John Rylands Library, Manchester

Opened in 1900, this library is part of the University of Manchester, one of the top five universities in the UK. This library offers limitless research potential for students. Whether you want to make use of the rich collections available, or simply explore the site, this library should be on everyone's must-see list.

The Mitchell Library, Glasgow

The Mitchell Library is one of Glasgow's most famous landmarks. On the top of the copper dome（圆屋顶） is a bronze statue of the Roman goddess, Minerva. Visitors can climb the dome for the city's most distinctive rooftop views.

注意：1. 词数 100 字左右； 2. 可以适当增加细节，以使行文连贯。 

参考词汇：退款refund 
To whom it may concern,

Yours sincerely,

Li Hua

增加：在缺词处加一个漏字符号(∧)，并在其下面写出该加的词。

删除：把多余的词用斜线(\)划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1.每处错误及修改均仅限一词。2.只允许修改10处，多者（从第11处起）不计分。

We were considering making an incredibly English magazine, and without hands-on experience we didn't know how to start it. To get professional instructions, we left for Beijing to visiting a chief editor of Beijing Review, the famous English journal. Although he was busy, he showed me around, explaining us the amazing history of the journal and its production process. Besides, he offered us lots of practical and valuable informations. What make us especially happy was that when he promised to give us continuous guidance. Filling with confidence, we are now beginning to handle our magazine.

Have you ever wished your vacation could meet all your(expect)? Well this is possible when you choose(go) on a cruise (游轮). Recently, cruises have become(popular) places than traditional forms of traveling.is not necessary to make reservations at different hotels, find places to dine, or arrange different transports in advance. Everything you can imagine is available whenever you want it on suchcruise ship.

Cruise ships are like miniature (小型的) cities on water. They are(full) loaded with restaurants serving all kinds of dishes. The staterooms (特等客舱) can be compared to rooms(find) in five-star hotels. The big difference isyou get to have a moving ocean view. What's more, there are activities designed for people of all ages and interests, and(vary) sports facilities like gyms and rock climbing walls as well as clubs and shops are also accessible. Quality entertainments like Broadway shows and live music(provide), too.

Around Thanksgiving, I flew to visit my family. A woman across the aisle 1 to push her suitcase into the tight overhead bin. When we landed, she was pulling, but the suitcase didn't 2 . I asked if I could help, 3 she replied, "It'll come. I got it in, and there has to be a way to get it out."

Her calmness and confidence 4 me, striking me as a recipe for cultivating (培养) resilience (抗逆力) in life. Resilience is the ability to 5 challenging circumstances, refocus and find ways back into a positive life. The woman's reaction to her 6 luggage was a beautiful example of cultivating resilience: "7 seeing crises as unsolvable problems."

The 8 situation might not be a "crisis", but you know how 9 a plane aisle can be when everyone is trying to get off the plane. The woman kept herself 10 by recognizing her problem had a solution.

The 11  reminded me of something that happened to me this past fall, when I took a solitary (单独的) hike along a rocky ocean path. I was enjoying myself in the fresh air, feeling12  as I picked my way from rock to rock and congratulating myself when I reached the end of the dock. Then I turned around and saw how 13  I had traveled, I felt myself slipping into nervous self-doubt. What if I 14  and twisted my ankle?

I took a deep breath and, like the woman on the 15 , realized with relief that I could certainly make it 16 . When I finally stepped back onto the shore, I not only felt 17 , but also confident and accomplished.

When 18 plant seeds of "I can't" in your mind, maybe you'll remember the woman on the plane. Wherever life has brought you, consider that there is a 19 to come back to yourself. You have the power of resilience within you whenever you are 20 it.

While sweat serves as the built-in air conditioner, sweating it out can have many: other surprising health benefits. 

It Eases Pain

Did you wake up with back pain?  Then the best way to relieve your pain is to work up a sweat. It might be very tempting to skip this step since pain will make you want to sit still. But actually increasing your heart rate and working up a sweat is one of the best things you can do for your pain while sitting around will just make you even more stiff and sore.

It Gets Rid of Toxins(毒素)

Our bodies are subject to a lot of toxins throughout our everyday lives. Sweating is a great way to expel (排出) those toxins from the body, which serves to better your immune system. It can also help get rid of substances like alcohol and salt.

Along with the sense of accomplishment from working out, working up a sweat releases endorphins (内啡肽), which make you happy. Sweating helps relieve stress and promote relaxation. Next time you're feeling stressed out or need a break to clear your mind, think about hitting up a hot yoga class or taking a few minutes for yourself in the sauna (桑拿) to ease your mind,

It Helps You Avoid Kidney Stones

One of the lesser-known benefits of sweating is that it lowers the risk of getting kidney (肾) stones. Research has shown that sweating helps you get rid of salt and keep calcium in your bones.  The more frequently you find yourself sweating, the better.

A. It Makes You Happier

B. Are you sore from yesterday's workout?

C. Pain is usually caused by toxins produced in the body.

D. Here are some top benefits of sweating in summer.

E. Sweating also helps prevent pollutants from entering the body.

F. This helps keep those elements from your kidneys where small stones will form.

G. They come from the pollution in the air, our food, and are created naturally in the body.

Mosquitoes carry malaria (疟疾), which kills thousands of people each year. Now some researchers are trying to use genetic engineering to make the annoying insects into partners in the fight against the disease.

For years, public health officials have tried to limit the disease by controlling mosquito populations. "But that approach is temporary," says Anthony James, a professor of biology and genetics at the University of California, Irvine, "Because mosquitoes are extremely tough little insects, and their populations can quickly rebound."

Therefore, James and his colleagues want to try a different approach: making mosquitoes themselves into malaria-fighting warriors, which is a complete departure from traditional ways of controlling malaria.

To understand how it works, it helps to understand the life cycle of malaria. The malaria pathogen (病原体) is a parasite (寄生虫) that grows inside humans. It's passed via mosquitoes that move from person to person, sucking blood. "If we can make the mosquitoes difficult for the pathogens to survive, we can wipe out the disease," he says. But making mosquitoes uninviting to malaria is a tough job.

To solve the problem, the team used a gene-editing technique called CRISPR. They started with genes from mice, whose immune systems do fight human malaria, engineered those genes, and then gave them to the mosquitoes.

It turned out the malaria-fighting antibodies which gene-edited mosquitoes produced worked very well. They reduced the number of parasites in the mosquito before they were passed to a human host.

James' team are now working on planning a field trial, which he hopes could be conducted on an island or in another isolated location.

But genetically changing wild animals does not sit well with environmentalists. "There's no need to engineer a mosquito," says Dana Perls, senior program manager for the emerging technology program at the non-profit Friends of the Earth. Perls points out that naturally occurring methods for reducing malaria appear to be showing promise, as does a new vaccine (疫苗) against the disease. "Why take unnecessary risks and release a species that can't be recalled once it's released into the wild?" she asks.