Have you ever rubbed your hands together when they get cold? Why do we do that? We do that for friction. Friction happens when two things that aren't very smooth (光滑的) rub together to make heat energy. The faster you rub two things together, the more friction you can make. Let' s discover friction!

WHAT YOU'LL NEED:
★Soap                ★Water           ★Your hands
WHAT TO DO:
★Make sure your hands are dry.
★Rub your hands together until you feel the heat of your hands.
★Now, use soap and water to get your hands very slippery (滑的).
★Try to make friction happen while your hands are slippery.
★Please write down what has happened.
LET'S TALK!
    Friction is an energy that happens when two things rub together. When friction happens, it makes heat! When your hands are slippery, they won't make very much friction and your hands won't get so hot.
DID YOU KNOW?
★Friction happens when you stop your fast running bike.
★Ancient people made fires by rubbing two pieces of wood together. Friction happened though they didn't know it. ___  __?         Friction is everywhere. Have you ever noticed situations where friction is happening? If not, ask your parents to take you out in a car. If it is not hot, touch the tires (轮胎) of the car before and after a short drive to see how much warmer they get from friction.

     Grace, usually known as the Home of Microsoft, is inside an office building in Redmond, Washington. Once you come into the building, you will feel that you're in a modern and future home.

      When you enter the building, Grace's voice, coming from a hidden speaker, tells you your messages. In the kitchen, you set a bag of flour(面粉) on a flat stone table. Grace sees what you're doing and makes a menu of flour-based foods on the table. Once you choose one, Grace gives you ingredients(配料).

There's also a notice board in the kitchen made of “intelligent(智能的) cloth” that works like a touch screen computer. You can deal with postcards and invitations and surf the net with the touch of a finger. The invitations could be encoded(编码). You can deal with them on the computer. It's part of Microsoft's Smart Personal Objects Technology, whose aim is to make every object more efficient(有效率的).

      “The day when your house becomes a member of your family is not far,” says Pam Heath, a manager of Microsoft. At the Andersen Windows Company, Jay Libby imagines that windows made of intelligent glass can be changed into TVs.

      “Nobody wants a television set,” says Libby. “What you want is the service it provides.” If the TV isn't improved, it will disappear in the future.

Home entertainment is one consideration for the future. At the Georgia Institute of Technology in Atlanta, scientists are designing systems that will allow old people to live better on their own. So Grandma's home can be cleverly designed to recognize(识别) her ways of waking, sleeping and movement. Family members will be told any change by their computers.

     We often read the Air Quality Index （空气质量指标） or AQI reported in the newspaper. The AQI helps us understand what the air quality around us means to our health. The AQI uses colors, numbers and words to tell us about the air. Let's see what these colors and numbers mean.

    Endangered dolphins are beautiful animals that needed to be saved. It may interest you to know there are about six different types of dolphins that are endangered. Many of them are river dolphins and they are very close to being lost forever if we do not take the time to care for them. The following is the reason why they are in danger.

    {#blank#}1{#/blank#}Dolphins can often get stuck(卡) in these nets and they may die. Another problem is the fact that many people and different countries will hunt for dolphins as food.

    {#blank#}2{#/blank#}When the oceans and rivers are polluted, it affects the very environment where these beautiful creatures are living. It may be important to also keep in mind that the dolphin is towards the top of the food chain.{#blank#}3{#/blank#} If these small animals are affected by the pollution as well, there really is no safe place for the dolphin to go.

    {#blank#}4{#/blank#}You can also pay attention to the land around you. Do not litter and stop if you do. Spend time on the weekend cleaning up trash in your area and recycle what you can. You play a large role in this whether you believe it or not. So, find out what your role is related to endangered dolphins and work towards a positive change.

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    Rivers are one of our most important natural resources(资源). Many of the world's great cities are located on rivers, and almost every country has at least one river through it that plays an important part in the lives of its people.

    Since the beginning of history, people have used rivers for transportation. The longest one in the United States is the Mississippi. The lifeline of Egypt is the Nile. To the people of India, the Ganges is great, but it is also important for transportation. Ships can travel along it for a thousand miles. Other great rivers are the Congo in Africa and the Mekong in southeastern Asia. The greatest of all for navigation(航海), however, is the Amazon in Brazil. It is so wide and so deep that large ships can go about two thousand miles up it.

    Besides transportation, rivers give food, water to drink, water for crops, and chances for fun and recreation for the people who live along their banks. In order to increase the supply of water for crops, engineers sometimes build a dam(坝) across a river and let a lake form behind the dam. Then people can use the water not only to irrigate(灌溉) their fields but also to make electricity for their homes and industries.

    However, large cities and industries that are located on rivers often cause problems. As the cities grow in size and industries increase, the water in the rivers becomes polluted with chemicals and other materials. People are learning the importance, however, of doing more to keep their rivers clean if they want to enjoy the benefits of them.

    Around the world, there are about 7,000 National Parks. Most of them cover huge areas of land where nobody lives. However, the National Parks in England include places where people live and work, as well as wild areas where there are few human activities.

    The National Parks in England are called "England's Breathing Spaces" because they are places where people can go to be in the open air, away from the dirt and noise of cities. They provide wonderful scenes of mountains, woods, grasslands and wetlands. And there are plenty of activities to do in all of the National Parks in England. Visitors can walk or ride bikes for fun. Many of the parks put on activities for families.

    Every year there are about 110 million visitors to the parks, bringing many benefits(益处) to the areas. At the same time, it creates problems, too.

    First, life can be difficult for local people. Car parks and roads are too crowded. Gift shops and cafes take the place of many everyday shops. Even house prices in some areas can become too high. Besides, country roads can be damaged, for too many people walk, cycle or ride horses on them. Roads can be rebuilt, but then they look less natural. Another big problem to the National Parks is litter. In the parks it is a danger to wild animals. Broken glass can also cause fires by focusing the rays of the sun. Such fires in wild places can be out of control.

    _______All National Parks in England are making more rules, which tell people how to take good care of their environment. If these rules are followed, the National Parks will be well kept and continue to give pleasure to many people for a very long time.