Ladies and gentlemen, I returned to this year in a time machine. In the year 2500, we are able to travel through time to any year in the history of the earth. This year is your last chance to change your lifestyle to save the earth.

    Beginning in the middle of the 20th century, a few people were worried about polluting the earth's water and air, but most people did not change their way of life.  Instead, they continued to pour(倒) dangerous chemicals and other waste into lakes and seas, to drive more and more cars and trucks, and to cut down trees.

By the year 2200, the earth's water was completely polluted. Scientists said that in the future there might be too many people on the earth. People could no longer drink water, and they had to use other types of liquids(液体).

So, by the year 2300, there were so many people that food became scarce. There was no water to grow food and all of the fish in the lakes and seas died because of pollution Terrier wars(战争) broke out between the rich and the poor. Scientists were working very hard to find another planet in space where humans could live on.

By the year 2400, the air was too polluted for humans to breathe. So we had to leave earth but only the rich were able to leave. Where did we go? Nowhere. And everywhere. You see scientists did not find another safe planet, so now we must travel around the universe in our space ships. We are still looking for a place to call our home.

    So, it is up to you to change history. There is still hope. You must change your lifestyle now, before it is too late.

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    Most people hope to have a memory which helps them succeed in study, work and life. Can memory be improved? Luckily, hundreds of studies in the past 50 years have already given us a definite answer.

    A healthy lifestyle keeps our brain young and memory sharp. First of all, it is necessary to have a healthy diet. Eating more food rich in B vitamins and vitamin E, such as vegetables and lean meat, helps you have a better memory. Doing exercise can keep your brain alive, too. Proper exercise provides much oxygen for the brain. Running, riding a bike, swimming and even walking two or three times a week are helpful. Moreover, getting enough sleep is important. Only when your brain gets a good rest, can it work well. The healthier your lifestyle is, the better your memory will become. But do not expect a sudden change－it takes a long time to make a difference.

    Memory stills help you remember things better. The following three are the most widely used. Chunking is a way of remembering a piece of information by cutting it into small ones. For example, to memorize a ten-digit telephone number 2127983630, you can divide the digits into three groups: first 212, then 798, and lastly 3630. This method is far more effective than remembering a string of 10 digits. Organization means organizing information into groups of the same kind. For example, trees, grass and flowers are plants; tigers, pandas, horses and cows are animals. Imagery is remembering newly learnt information by using your imagination and connecting it with something that you are familiar with.

    However, memory skills will hardly work if you don't understand the information. What's more, only a regular review can make the memory last long. That is why students are always advised to go over what they have learnt and then use it as regularly as possible.

    Human brains are like muscles that needs nutrients and exercise to become stronger. If you make a few lifestyle changes and try some memory skills, you can certainly improve your memory.

    Climbing Mount Qomolangma, the World's highest mountain, has now become more difficult. The government of Nepal asks climbers to come down the mountain with at least 18 pounds of garbage. That's the average amount of garbage a climber leaves behind on Mount Qomolangma.

    Climbers would leave garbage along the way. This helps climbers keep their bags light, so they would have energy to reach the summit.  The garbage problem in Mount Qomolangma is not new. In 2013, climbers carried down a total of four tons of garbage.

    The new rule came into effect in April of 2014. To make sure it is followed, climbers will have to hand in some money to the officials before they climb the mountain. When they climb back down the mountain, the officials will check them to make sure they bring down the 18 pounds of garbage. If they do, their money will be given back to them.  If not, climbers won't get their money back. Also, the officials won't let these people climb the mountain again.

Is It Better to Read Books or Listen to Them?

    We often think how fast we learn something depends on how smart we are. If your brain is taking in material quickly, you're clever; if not, well, that doesn't say great things about your IQ. But science shows context (上下文) and technique (技术) actually play a big role in how fast we learn, and even small changes – like the way you use to read – can make a big difference.

    Audio (音频的) books have plenty of advantages: you can enjoy them anywhere, even in the car, and not printing books saves trees. Poor readers also often find them more interesting. But according to the latest research, if your goal isn't to pass the time in traffic, but instead to learn something difficult, you should choose a physical book.

    In a recent opinion piece in the New York Times, psychology (心理学) professor Daniel T.

    Willingham mentioned a 2010 study where 48 students either read or listened to an article about child psychology. Although the students spent the same amount of time with their material and did about the same number of distracting (分散注意力) activities while they absorbed the information, they scored very differently on a 10-item quiz later. Generally, the readers scored 81 percent but while the listeners scored 59 percent. Why does listening vs reading material have such a great effect on learning?

    Willingham explains that first, most of us read more slowly than we listen (especially when pausing and rereading), and when you're trying to absorb new information, slower seems to be better. "About 10 to 15 percent of eye movements during reading are actually regressive – meaning the eyes are going back and re-checking," he explains to TIME. "This happens very quickly…"

    Second, books offer visual cues (可视线索) that help our brains organize and understand new information. Things like chapter breaks, subheadings, and lists help us in making sense of the material and understanding how it fits together. You lose all that when you go the audio way.

    The bottom line is simple: Don't feel shame about passing your time in traffic with an audio book. However, be aware of audio's limitations when it comes to studying, and seriously consider choosing good old-fashioned reading instead.