According to a national study, in the summer of 2013, the long-term(长期的) warm weather in the UK has made the number of butterflies increase.

    Around 46,000 volunteers(志愿者) took part in the year's Big Butterfly Count(统计), and they found 830,000 butterflies.Volunteers were asked to make a record.They would record how many times they found one of 21 different kinds of butterflies.

    Later, the scientists used the records to find out how many butterflies of different kinds were found across the country.Then, they compared the results to the year before.They found that there was a rise in the number of 15 kinds of butterflies, and some of them went up by 50% compared to recent years.They said the increase in butterfly numbers was a result of warm weather.

    However, scientists also said that the number of butterflies was in decline(下降) as a whole, and that we might not see the same result the next year.

    Richard Fox, who works for Butterfly Conservation, said, “UK butterflies are in long-term decline.Studies have been done since the 1970s.They show that UK butterflies have declined in type and number.”

    He added, “We must halt the long-term decline of these beautiful creatures(生物).The only way is by stopping the damage that has been done to the butterflies' habitats(栖息地) across the UK.”

D

    For many years, scientists have said that the earth is getting warmer. Now they have found something new—hot cities! In the southern US, they have found that cities become very hot in summer. For example, the city of Atlanta in Georgia has roof(屋顶) temperature of up to 50^oC while it is 27℃ in the streets! At night, the outside of buildings stays so hot that the heat of the city causes storms over the city!

    China also has the same kind of problems. Every year more farmland is used for factories or offices. More housing is needed, too. As people become richer, they buy more cars. New roads are needed and new car parks are built in the city centers. This all makes cities hotter.

    It isn't easy to change the situation. City planners say that we should plant more trees in the middle of cities. Every new street should have trees on both sides, they say. Trees make the temperature lower, so we should have more trees in our parks and squares. We should also paint our roofs white. If we do this, they do not become so hot. Every roof in a hot and sunny country should have solar(太阳的) roof panels. The electricity from these can be used to run the air conditioners (空调)in the buildings.

    People continue to cut down forests around the cities. This makes the problem worse. Cities are growing faster and faster. By the year 2025, four fifths(五分之四) of the population will be living in cities. If we go on like this, there will not be enough farmland to feed everyone in the world.

    Have you ever heard someone use the phrase"once in a blue moon"？People use this expression to describe something that they do not do very often．For example，someone might say that he tries to avoid eating sweets because they are unhealthy，but will eat chocolate"once in a blue moon"．Or someone who does not usually like to go to the beach might say"I visit the shore once in a blue moon．"While many people use this phrase，not everyone knows the meaning behind it．

    The first thing to know is that the moon itself is never really blue．This is just an expression．In fact，the phrase"blue moon"has to do with the shape of the moon，not the color．

    As the moon travels around the earth，it appears to change shape．We connect names with certain shapes of the moon．For example，when we can see a small part of the moon，it is called a crescent moon．A crescent is a shape that looks like the tip of a fingernail（指甲尖）．When we cannot see the moon at all，it is called a new moon．When we can see the whole moon，it is called a full moon．Usually，there is only one full moon every month．Sometimes，however，there are two full moons in one month．When this happens，the second full moon is called"a blue moon"．

    Over the next 20years，there will only be 15blue moons．So you can seldom see a blue moon． This fact has led people to use the expression"once in a blue moon"to describe things they don't often do in their lives．

    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 your brain memory sharp. First of all, it is necessary to have a healthy diet. Eating more food rich in Vitamin B 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 needed 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 don't expect a sudden change-it takes a long time to make a difference.

    Memory skills 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 smaller ones. For example, to memorize a ten-digit telephone number 2127983630, you can divide the digits into three groups: firstly 212, then 798, and lastly 3630. This method is far more effective(有效的) 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 after one day and then after three days, and then use it as regularly as possible.

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

    The world uses about a thousand million (百万) tons of water a day. Water is a human right and everyone should have their share. Yet more than 700 million people around the world have trouble getting clean, safe water.

    Treating wastewater is a good way to provide fresh water for us. And it also helps the environment by keeping waste out of rivers and oceans. 80% of wastewater around the world is not treated at all, and it is running into oceans. But now we have got the technology to treat and reuse the wastewater.

    While 75% of our planet is covered with water, only about 2% is fresh water—that comes from rivers, lakes, ice and snow. The rest, 98% of the water, is in seas and oceans. It is too salty to drink. Then desalination businesses come in. More than 19,000 factories have been built around the world, mostly in coastal countries. They process (加工) more than 92 million tons of water every day. But the technology they use requires a lot of energy.

    Scientists are working to create a less costly technology. They want to produce 20 times more clean water and make sure everyone has enough. But for now, the world still faces each day with not having enough water for everyone.

    We often find that weekends and holidays feel so short while classes and work feel so long. Actually, though, we know that this is not true. But we still wonder where that strange feeling comes from.

    In fact, this is one of the ways that we're tricked by time, according to the website. All that S interesting. The website lists several wrong impressions (印象) we often have about time. Let's have a look.

    First of all, emotions affect (影响) our time-keeping abilities. Negative emotions (消极情绪). especially anxiety and boredom, make time seem longer because they make us concentrate (集中) more on the passage of time. However, when we are enjoying ourselves, we pay more attention to what we are doing and are likely to lose track of (失去对……的意识) time.

    Here is another example. In 2007, a group of scientists carried out a test. In the test, people fell 50 meters into a safety net and were then asked about their experience. Although the experience took shorter than 3 seconds, the people thought it was much longer than it actually was.

    This is because of the way our bodies reply to danger, according to the scientists. Our bodies produce a chemical called adrenaline (肾上腺素) when we are faced with danger. It allows us to concentrate better so that we can stay alive. As a result, we are able to remember far more details (细节) over a short period of time, which makes it seem like time is going more slowly.

    Another situation when we make mistakes about time is when we take afternoon naps (午觉). Have you ever had trouble telling what time it is after a long nap? That's because the best amount of time for a nap is 20 minutes. After 20 minutes, you enter a new stage of sleep called slow-wave sleep. If you wake up mid-way in this stage, it will take a while before you can correctly perceive (感知) time again.

    Yes, time can be mysterious (神秘的) and there is no way to control it. So, perhaps the best thing to do is to make good use of every minute.