Song Tao worked very hard at his study. , he passed the exam easily.

    Today people in the world have a busy life and they often feel unhappy under too much pressure. In fact, keeping happy1 important and necessary for everyone.

    Most people want to be happy, 2 few know how to be happy. Money and success can bring pleasure, however, it 3 long. Actually, happiness depends on 4.

    Here are 5 ways to help to be happier.

    The first thing is to enjoy the simple things in life. We often spend too much time thinking about the future—for example, going to a famous university or getting a good job. You should enjoy simple pleasure in life, such as 6 a good book, listening to your favorite music or spending time with good friends and so on.

    The second secret is to be 7. Many people enjoy dancing or playing sports. You can forget all your problems and only think about the activity you are doing.

    8 secret, helping others is a good way to keep healthy. You always feel happy when you do 9 for someone. You can do chores for your parents, help a friend or a classmate with his or her study and go shopping to buy food for an old neighbour.

    In a word, learning to be happy is good for your 10.

    A Swiss inventor drove his solar-powered car(太阳能汽车)to a school in Shanghai. There is not enough oil in the world now. As time goes by, it be013es less and less, so what are we going to do when it runs out? Perhaps we will go back to using horses, carriages and bicycles.

    In the Second World War, some people didn't use gas made from petroleum(石油)in their cars. They made gas from wood and plants instead. The car didn't go fast, but they ran, so this was better than nothing. However, in the future, we can't cut down all our trees to make gas. We need our trees for other things, too.

    Besides different types of gas, we can also use electricity to run our cars, but first we must make the electricity! Some countries have coal and they make electricity with that, but we might not always have coal, either. Other countries have big, strong rivers, and they can use the power of water to turn turbines(涡轮机)and make electricity more easily and cheaply.

    We are also able to get power from the ocean tides. We put turbines into the mouth of the river. Then the tide comes in, the water turns the turbines and then it goes out, it turns them again.

    Which of these ways will be used to run our cars in the future?