A new study warns that about thirty percent of the world's people may not have enough water by the year 2025.

    A private American organization called Population Action International did the new study. It says more than 335 million people lack enough water now. The people live in 28 countries. Most of the countries are in Africa or the Middle East.

    P-A-I researcher Robert Engelman says by the year 2025, about 3,000 million people may lack water. At least 18 more countries are expected to have severe water problems. The demand for water keeps increasing. Yet the amount of water on the earth stays the same.

    Mr. Engelman says the population in countries that lack water is growing faster than in other parts of the world. He says population growth in these countries will continue to increase.

    The report says lack of water in the future may result in several problems. It may increase health problems. Lack of water often means drinking water is not safe. Mr Engelman says there are problems all over the world because of diseases, such as cholera, which are carried in water. Lack of water may also result in more international conflict. Countries may have to compete for water in the future. Some countries now get sixty percent of their fresh water from other countries. This is true of Egypt, the Netherlands, Cambodia, Syria, Sudan, and Iraq. And the report says lack of water would affect the ability of developing to improve their economies. This is because new industries often need a large amount of water when they are beginning.

    The Population Action International study gives several solutions to the water problem. One way, it says, is to find ways to use water for more than one purpose. Another way is to teach people to be careful not to waste water. A third way is to use less water of agriculture.

    The report also says long-term solutions to the water problem must include controls on population growth. It says countries cannot provide clean water unless they slow population growth by limiting the number of children people have.

    Thousands of persons in Peru are suffering from the disease cholera. Medical experts say it is the first time in their century that cholera has reached the western part of the world. The Untied States Centers for disease Control says the kind of cholera has been spreading throughout the world since 1961. It was discovered that year in Indonesia. Since the first case in Peru, more than sixteen thousand people have been affected and about one hundred have died.

    Cholera is caused by polluted food and water. People become infected (传染 ) when they eat the polluted food or drink the polluted water. If untreated immediately, they may die within hours. Most victims however , can be saved. treatment includes drugs and replacement of body fluids ( 液体) directly into the blood.

    Medical researchers have developed a vaccine ( 菌苗) medicines to protect against cholera. But the vaccine is only about 50% effective. And it protects against cholera for only about six months. Medical experts say the best way to fight cholera is to prevent it. They also say people should not eat uncooked food or food that has not been cooked long enough. People who live in areas where cholera has been found should wash their hands before eating and cooking. They should drink only water that has been boiled or made pure with chemicals.

    A student is learning to speak British English. He wonders: Can I communicate with Americans? Can they understand me? Learners of English often ask: What are the differences between British and American English? How important are these differences?

    Certainly! There are some differences between British and American English. There are a few differences in grammar. For example, speakers of British English say “in hospital” and “Have you a pen?” Americans say “in the hospital!” and “Do you have a pen?”. Pronunciation is sometimes different. Americans usually sound theirs in words like “bird” and “hurt”. Speakers of British English do not sound theirs in these words. There are differences between British and American English in spelling and vocabulary. For example, “color” and “honor” are British, “color” and honor” are American.

    These differences in grammar, pronunciation, spelling and vocabulary are not important, however. For the most part, British and American English are the same language.

    In a research carried out in the UK, it was found that only four out of every five employees were happy at work. Surprisingly, it wasn't the pay or the love for the work that made people happy. Instead, friendly, supportive colleagues and a good manager have been found to be the primary causes of happiness at work. So how do you develop a sense of joy on the job? Here are some suggestions.

    Happiness is a state of mind, so staying happy at work is completely based on a positive attitude towards your job. Focus on the bright side of the work rather than keep talking about what makes you unhappy.

    Challenge yourself and take charge of your own growth in your career. Boredom is one of the primary factors that cause people to change jobs. Find new challenges and it's a great feeling to take control over what you do and see a task through.

    Having co­workers you like and enjoy working with is a feature of happiness in the workplace. Talk to people, get to know them and try to get along well with them in the workplace. Meeting new people and getting fresh views can help you to keep yourself interested in your work.

    Complete your tasks, no matter how disagreeable or tough they might be. This gives you a sense of achievement and encourages you to work towards your goals in future.

    Sitting and staring at your screen all day long isn't going to help you. Instead, take breaks and go outside for some time. For example, go out for a few minutes to feel the breeze (微风). Eat your lunch outside or work for a few minutes during that hour, which helps you stay happy at work.

    Physics is a different world now. Will there ever be another Einstein?

    Scientists say a new Einstein will appear, but it may take a long time. After all, more than 200 years separated Einstein from his nearest rival (对手) , Isaac Newton. Many physicists say the next Einstein hasn't been born yet, or is only a baby now. That's because the searching for a unified(统一的) theory that would explain all the forces of nature has pushed current mathematics to its limits. New math must be created before the problem can be solved.

    But researchers say there are many other factors working against another Einstein appearing anytime soon. For one thing, physics is quite a different field today. In Einstein's day, there were a few thousand physicists worldwide, and fewer theoreticians. Education is different, too. One extremely important aspect of Einstein's training that failed to be considered is the philosophy he read as a teenager. It taught him how to think theoretically about space and time.

    And he was a skilled musician. The interplay between music and math is well known. Einstein would fiercely play his violin as a way to think through a knotty physics problem.

    Today, universities have produced millions of physicists. There aren't many jobs in science for them, so they go to Wall Street and Silicon Valley to apply their analytical skills to more practical and rewarding efforts.

    Besides, those who stay in science don't work alone. It's very difficult to imagine an independent person like Einstein ever tolerating this.

    A new study suggests climate conditions in the Sahara Desert, one of hottest, driest and most deserted areas in the world, have changed from wet to dry a about every 20,000 years.

    But previous evidence has suggested the Sahara did not always experience such extreme heat and dry conditions. At times, the Sahara Ranged to a very wet climate. This permitted plants and animals to develop and grow and led to the creation of human settlements. Now, they have discovered more evidence, which, the lead researcher David Mc Gee says, supports the idea that the Sahara's climate kept changing between wet and dry about every 20,000, years.

    McGee reported these climate changes were mainly driven by changes in the Earth's(地轴)as the planet travels round the sun .This process affects the amount of sunlight between seasons. Every 20,000 years the Earth receives more strong summer sunlight. When the Earth's axis changes again, the amount of sunlight is reduced. This season change happened continuously every 20,000 years. The other part of the season produced rainy conditions, resulting in a wetter, greener, plant-rich environment. When the rainy activity weakens, the climate becomes hot and dry, like the Sahara remains today.

    The scientists based their research on dust collected from ocean sediment(沉积物)in the Atlantic Ocean bottom off the coast of West Africa. The dust contained layers (层)of ancient sediment built up over millions of years. Each layer could contain traces of Saharan dust as well as the remains of life forms. This information was used to assess over what time period the dust had built up. This led to the overall finding that the Saharan changes from wet to dry climates happened every 20,000 years.

David McGee said that today we only see the Sahara Desert as an extremely deserted and "inhospitable" place. The new study suggests that the area's climate has changes between grasslands and a much wetter environment, and back to dry climates, even over the last quarter million years. McGee says he thinks the latest research can be valuable in studying the Sahara's history as it relates to human settlement.