Parents today also worry about their children's diets. Some doctors give the following advice：

    Water has always been necessary for our health. Then what kind of water do you drink, tap water or bottled water? Do you get a healthier, safer and more refreshing(提神的) drink when you buy bottled water off the shelf? My answer is "no", and doing so hurts the environment and your wallet.

    First of all, there are no studies showing that bottled water is better for you, and in fact, it may be less safe than tap water. A study of over l, 000 people in Belfast found that they couldn't tell the differences between tap water and bottled water when asked which was purer, more pleasant, natural and refreshing. Bottled water can come from springs(泉水) or from the mountains. It can also be treated, for example, to have iron(铁) removed. It is reported that there is around 82.8g of CO₂ for a half-liter(半公升) bottle. This will be harmful to people's health when everyone's drinking it. However, bottled water is popular with many people. Its success is from excellent marketing and our laziness in filling reusable bottles with tap water.

    Secondly, bottled water can cost between 500 to 1, 000 times more than dap water. In 2015, the UK drank 2.4 billion liters o of bottled water, and by 2016 this had risen to 2.6 billion liters. Yet, you get this from the tap, for free.

    Besides, recycling is improving, but in America, it is said that only a quarter of bottles can be used again. So is it really so much better that it is worth both paying for and harming the earth? Or should you stop buying it?

    As a general rude, I believe that most of us should enjoy more tap water, and stop using so many bottles.

    Thousands of years ago, people didn't know that the Earth moved. They thought the sun really did move across the sky. The Greek god Helios was said to drive the sun across the sky with his chariot (战车). But now, the way people think has changed. Nowadays, it is the sun that drives a "chariot" around the sky.

    What do I mean by this? Well, quite simply, there is now a plane (or "chariot") that is powered by the sun. It has special parts on its wings. These parts absorb (吸收) power from the sun. They absorb so much power that the plane can still fly even at night. In Greek mythology (神话), Helios had to take a break at night. It seems we're finally even more powerful than the gods themselves.

    This plane is called Solar Impulse. It will fly across the US in May. This is very important for the future of the world.

    Why is solar energy (太阳能) important? Well, other kinds of energy are known to cause problems. If you live in China, you've probably noticed the pollution. This is caused by burning coal and gas to make energy. The heat and chemicals created by burning these things give us power. But if we use power from the sun, we don't have to burn anything and there will not be any pollution.

    Solar energy is not entirely ready yet. It needs to be improved. But the best thing about it is that, unlike coal and gas, it doesn't run out. The Solar Impulse plane could pretty much keep flying forever. Of course, the sun's light will eventually run out too one day, but not for another 5 billion years. That's a pretty long flight.

    The monarch is one of the most beautiful butterflies. It is famous for its yearly migration（迁徙）from the northern part of North America to Mexico, There, millions of monarchs spend the winter together in one small area. This migration is one of the greatest wonders of nature. Yet this behavior has now put the monarch at risk.

    Every September, millions of monarchs from the United States fly to Mexico. After about two months of flying time, they reach their sanctuary(庇护所)in central Mexico. Then, in the warm climate of private and quiet valleys, far from most human activity, the butterflies create one of nature's great scenes. They cover every tree with bright color. The show lasts until spring, when the butterflies return north.

    While they are all crowded together, the monarchs are highly weak. If the environment in those valleys was disturbed, the whole species could be hurt or even die out. That is why for many years scientists who knew about the monarchs' winter sanctuary kept the location a secret.

    In recent years, however, the monarchs' secret has been discovered. Today, the butterflies' winter sanctuary is crowded with tourists, who disturb the environment. Worse still, local farmers who need more land to farm have begun to take up the area. They are cutting down trees, making it difficult for the butterflies to survive. They should not farm in the monarchs' sanctuary.

    People should act immediately to protect the species' winter sanctuary. Local farmers must be helped so that they no longer need to take land from the butterflies. Tourist visits to the butterflies' hidden valleys must also be limited. Unless these steps are taken soon, in a few years the monarch butterfly of North America may be just a beautiful memory.

    Life in the future will be different from life today. Between then and now many changes will take place. But what will the changes be?

    The population is growing fast. There will be many people in the world and most of them will live longer than people live now.

    Computers will be much smaller and more useful, and there will be at least one in every home. And computer studies will be one of the most important subjects in schools then. People will work for fewer hours than they do now and they will have more free time for sports, watching TV and travelling. Travelling will be much cheaper and easier. And many more people will go to other countries for holidays.

    There will be changes in our food, too. More land will be used for building new towns and houses for all the people. Then there will be less room for cows and sheep, so meat will be more expensive. Maybe no one will eat it every day. Instead, they will eat more fruit and vegetables. Maybe people will be healthier. Work in the future will be different, too. Robots will do dangerous and hard work. Because of this, many people will not have enough work to do. This will be a problem.