D

    Astronauts (宇航员) face many problems when living in space stations. One of them is food. People on Earth put together all the meals first and then send these meals to space stations by space shuttle. Because the food has to last a long time (sometimes up to three months), people have to store a lot of it in cans. The space station does not have a fridge, but it has a cool room to keep fruit and vegetables fresh. Astronauts also eat many other foods such as dried meat that do not need special care.

    Without the help of gravity sitting down to eat can be difficult. Astronauts sometimes have to fix themselves to the wall while eating. They also have to be very careful so that food does not float away.

    What will our world be like in 2020 We aren't quite sure, but it's interesting to make some predictions.

    Languages

    English should still be the most popular language, but Chinese should be the second. Now, many foreign people are studying Chinese as their second language.

    Water

    Water will become as expensive as oil because many rivers will disappear. We will have to save water and pay more for clean water.

     Education

     More students will study online. Students from all over the world may study together on the Internet.

    In the universe, as we all know, there is the sun, the moon, the earth and a good many stars. Through our geography lessons, we know the earth goes around the sun, and the moon goes around the earth. We have day and night because the earth keeps turning all the time. When our part of the earth turns to the sun, it is day. When our part of the earth turns away from the sun, it is night.

    Just because the moon is closer to the earth than the sun, it looks much bigger than the sun. Big things will look smaller when they are further, and small things also look bigger when they are nearer.

    The sun is big enough to give out very strong light. The moon can't give any light at all, but it looks quite bright, too. Why? In fact, the light from the moon comes from the sun. The moon looks much bigger and brighter than the stars. But actually (事实上) the stars are much bigger and brighter than the moon. They look smaller than the moon also because they are further away from the earth.

    There are many other planets in the universe. But of all the planets, only on the earth there are living things and people can only live on the earth, too. But at 9:00 a.m. on October 15th，2003, Chinese pilot Yang Liwei was sent up to space. He stayed there for 21 hours. It was the first time for Chinese to get into space.

B

    All over the world in the twenty-first century, people can get new energy in many ways.

    Energy from the wind. People use the power of the wind．It is a clean source(来源) of energy, and there is lots of it. However, if the wind does not blow, there is no wind energy.

    Energy from the water. When water moves from a high place to a lower place, it has the power to make electricity. Waterpower produces enough energy for 40, 000 people in a town. Waterpower gives energy without pollution. However, people have to build dams(大坝) to use this energy, and building dams is very expensive.

    Energy from the earth. There is heat in the rocks under the earth. Scientists use the heat to make geothermal(地热的) energy. San Francisco gets half of the energy from geothermal power. This kind of energy is cheap, but it is only possible in a few places in the world.

    Energy from the sun. Solar panels(太阳能电池板) on the roofs of houses and buildings can turn energy from the sun into electricity. These panels can create enough energy to heat the whole house during winter. Solar power is clean and plentiful(丰富的), but when the weather is bad, it can't produce power．

C

    On a very hot day，it can be hard to know what to do to feel good．If we run around，we may feel dizzy and sick to our stomachs．This is because our body can't get rid of the extra heat．However，if we just sit and do nothing，we may feel restless and bored．Are there things we can do to feel good when we are hot? Yes! Playing in water is one way to feel cooler．Of course，people with a pool，river，lake or ocean nearby can play in the water very conveniently．People don't have these can still play in water too．Taking a cool bath or shower can feel good on a hot day．On hot days，you can lose two gallons(加仑)of water in one day，so many doctors agree that you should try to drink at least 16 glasses of water to keep the water balance in your body． Mixing a little juice into your water is a good way to help you drink plenty of water．The food we eat also makes a difference in how we feel in the heat．Cold foods，such as ice cream and drinks with some ice can cool down our bodies．Fruits and vegetables are easy for the body and refreshing．Plan a healthy menu for a hot day．

    Most of us know that Ikea is the world's biggest furniture company. However, did you know that it's also a pioneer in environmental protection?

    Ikea says it's working hard to improve the environment. The company has made huge efforts to cut the carbon emissions(碳排放)of its suppliers(供应商).Over the past five years, Ikea has helped its suppliers become 18 percent more energy-efficient. It managed to do so by bringing its suppliers together. The one that produces the least carbon emissions will be praised.

    Ikea has also invested(投资)heavily in clean energy. The company now operates more than 300 wind turbines(叶轮机)around the world. It has also set up nearly 750,000 solar panels(太阳能嵌板)on the roof of its stores. As a result, Ikea can produce 71 percent of the energy it uses, which are all from clean sources. In some countries，such a} Denmark and Finland，the company produces as much energy as it uses.

    Ikea has been buying forests as well. It owns nearly 750 square kilometers of forest.

    Last but not least, Ikea has tried changing customers' behavior(行为).It does so by improving product designs. In 2015, Ikea changed all of its lighting products into LED. This change alone, it says, has saved lots of electricity.