Transparent animals let light pass through their bodies the same way light passes through a window. These animals typically live between 

the surface of the ocean and a depth of about 3,300 feet—as far as most light can reach. Most of them are extremely delicate and can be 

damaged by a simple touch. Sonke  Johnsen, a scientist in biology, says, “These animals live through their life alone. They never

touch anything unless they're eating it, or unless something is eating them.”

And they are as clear as glass. How does an animal become see-through? It's trickier than you might think.

      The objects around you are visible because they interact with light. Light typically travels in a straight line. But some materials slow and

 scatter(散射) light, bouncing it away from its original path. Others absorb light, stopping it dead in its tracks. Both scattering and absorption

 make an object look different from other objects around it, so you can see it easily.

But a transparent object doesn't absorb or scatter light, at least not very much, Light can pass through it without bending or stopping.

That means a transparent object doesn't look very different from the surrounding air or water. You don't see it —you see the things

behind it.

   To become transparent, an animal needs to keep its body from absorbing or scattering light. Living materials can stop light because they

contain pigments(色素) that absorb specific colors of light. But a transparent animal doesn't have pigments, so its tissues won't absorb

 light. According to  Johnsen, avoiding absorption is actually easy. The real challenge is preventing light from scattering.

Animals are built of many different materials—skin, fat, and more—and light moves through each at a different speed. Every time light

moves into a material with a new speed, it bends and scatters.Transparent animals use different tricks to fight scattering. Some animals are

simply very small or extremely flat. Without much tissue to scatter light, it is easier to be see--through. Others build a large, clear mass of

 non-living jelly-lie(果冻状的)material and spread themselves over it .

    Larger transparent animals have the biggest challenge, because they have to make all the different tissues in their bodies slow down light 

exactly as much as water does. They need to look uniform. But how they're doing it is still unknown. One thing is clear for these larger animals, staying transparent is an active process. When they die, they turn a non-transparent milky white.

【1】A safari park is a park in which wild animals are kept. They are mainly located in east or central Africa. They often occupy a very wild area, with mountains and rivers. To visit the park and look at the animals, people have to drive around in a car for a few of hours because the park is huge.

【2】In south Africa there is a safari park, which contains all sorts of wild animals like lions, elephants, rhinoceroses(犀牛), zebras, wild pigs, deer and giraffes.

【3】There is a wild road leading through the park, but nobody is permitted to walk on the road. Anyone traveling in the park has to go in a car because wild animals may fiercely attack people. From the car he may see almost every types of African wildlife. Some of these are getting scarce (稀有的) because people kill them for various reasons. For example, rhinoceroses are killed for their horns (角), which are used in traditional Chinese medicines for colds and headaches. Perhaps they will be seen only in museums and books one day.

【4】Travels may buy food for the animals. They can feed them when they tour the park. Of course, they should not feed them in a close distance because the wild animals may attack people. In addition, they should only give proper food to the animals.

【5】A traveler may carry a gun with him in his journey. The gun is given to him by the government. However, it is not used for hunting. In fact, a seal(封条) is fixed to it. The traveler may fire at a wild beast to defend himself in case he is attacked. However, he has to prove to the government that he has been attacked and that he has not fired at a harmless animal.

    For many of us, talking about money is embarrassing, especially revealing our income and spending habits in public. So it's no wonder that seeking investment advice from computer program is so popular.

    Consultancy firm Accenture found that 68% of global consumers would be happy to use robot-advice to plan for retirement, feeling it would be faster, cheaper, and fairer than human advice. “Many of our customers say they feel awkward in face-to-face meetings, preferring an online experience where they don't feel nervous,” says Lynn Smith, a director of robot-advice firm Wealth Wizards. So how does robot-advice work and is it really any better than traditional financial advice?

    Robot-adviser firms use algorithms (算法) to analyse your financial situation and goals and then work out an investment plan to suit you. Basically, you answer lots of questions online about your income, expenses, family situation, attitude to risk and so on, and then the algorithm allocates (分配) your savings to a series of investments, from index funds that aim to imitate a particular stock market index or sector, to fixed-income bonds.

    Robot-advice is certainly growing in popularity. But are we really happy to give up the human adviser completely? “No” is the short answer. Accenture finds that a significant proportion of us still want human interaction, particularly when our finances are complex. “When a customer needs advice surpassing a number of different regulatory regimes, human advice will be required, says John Perks, managing director of life and pensions at UK insurer LV, which launched its Retirement Wizard robot-advice service two years ago.

    The truth is that only about a quarter of funds managed by clever humans overcome the market as a whole, so when you take into account the much higher management fees you pay for that kind of service, the performance difference is likely to be marginal (微不足道的) for most of us.

    The robots may be coming, but in this case at least, they seem to be on the side of the small investor trying to save for a comfortable retirement.

    Many years later, when people recall the 2018 Russia World Cup, they will remember many things. With the tragic ending of the defending champion Germany, Mexico has triumphantly and suddenly lost three goals in the face of Sweden. But people will never forget the back of a lonely person. That is Lionel Messi.

    31-year-old Messi took off the green armband of his left arm and suddenly fell out. In the recent match, he and his team lost the game against France. The 19-year-old striker Mbappé relentlessly ripped apart the Argentine defense line and scored twice, which made a great contribution to the victory of France.

    On this planet, anyone who knows a little about football knows the name Lionel Messi and his golden years from 2007 to 2017.

    In 2007, 19-year-old Messi tied Real Madrid three times with a hat-trick, and began his legendary career.

    In the past ten years, Mr. Football, the Golden Globe Award and the Golden Boot Award have been taken over by him.

    He led Argentina and Barcelona to make a name for themselves in the world, and has a brilliant record in the Champions League, America's Cup and World Cup.

    Eleven years later, Messi stood on the Kazan Stadium. After four World Cups, he knew that this might be the last time he led Argentina to the World Cup.

    Since 1986, Argentina has never won a championship again. As a captain, he has a great responsibility, even stating that he would withdraw from the national team if he did not win the championship this year.

    This is a prophecy.

    Messi, who eventually failed to save the game, did not receive any interview after standing up on the lawn; leave behind only a legendary image for the world.

    To travel abroad, we often meet the problem of what to take and how to take it. Take as little as possible. Choose clothes for your use in different kinds of situations and when you have made your final choice, take half of it! It's always a big problem to take too many things, and anyway if necessary, you can buy what you need in America. Things like jeans, T-shirts and other clothes are good buys in the US. If you hunt around you can usually find something on sale.

    Whatever baggage you take, make sure it is easy to take. Getting on and off buses and trains, even just changing planes, can be a test if your bags are too heavy or too many. The best way is to take one holdall, like a suitcase or a backpack, and then a smaller bag. Even when you have to check in your holdall, at the airport or bus station, you can keep all your money and documents by your side. It is also a good idea to keep a change of clothing in your shoulder bag in case your suitcase or backpack gets lost by an airline or a bus company.

The means you choose to travel around the US will depend on your money, you time and something else. Since there are certain discounts available to travelers who buy their tickets outside the US, it is a good idea to make travel plans before you go. Also, when you buy your tickets outside the US, you save the eight percent sales tax. Travel is like everything else in America—you have to shop around for the best busy. Never be afraid to ask for the cheapest fare. The clerk seldom offers you the cheapest one.

    The TED speaker series features "ideas worth spreading". With over 1,400 to choose from, we've selected a few that are perfect for students.

    ⒈Larry Smith: Why you will fail to have a great career

We humans may have an unfavorable habit of making excuses for ourselves or being too confident about ourselves. Accordingly, Larry Smith, a professor of economics at the University of Waterloo in Canada, tells us why most of us will fail to have a great career. Luckily, as he puts it, there is a way out—follow your heart, as long as it is good for your career.

    ⒉Andy Puddicombe: All it takes is 10 mindful minutes

Between dance team, volunteering and –oh, right—lectures, your life's crazy factor(因素)is about to go way up. In this entertaining and informative talk, Mindfulness, expert Andy Puddicombe teaches us how to be "more healthy, more mindful and less distracted" by taking just 10 minutes out of the day to be "more present".

    ⒊Shane Koyczan: To this day…for the bullied(欺凌)and beautiful

    This talk is sure to stay with you. Shane Koyczan's "To This Day" is an affecting spoken-word poem about bullying and being different that gained over 10 million views on YouTube. In this talk, Koyczan gives a live reading of the poem, along with some stories about his background.

    ⒋Susan Cain: The power of introverts(性格内向者)

    Does a cup of tea and a good book sound like a perfect Friday night? In this personal talk, Susan Cain argues that introverts have talents and abilities. Our culture may value being outgoing, but the world needs all kinds.