Monarch butterflies from eastern Canada make the most amazing journey in the insect world. Each year, this butterfly travels about 3000miles to its winter home in central Mexico(墨西哥). How can it fly so far? And why does it make this long and dangerous trip? Scientists still don't have an answer.

 For many years, people in Mexico wondered where the orange-and-black butterflies came from every winter. Then, in 1937, a scientist started to follow and study the butterflies. For the next 20 years, he discovered that one butterfly started its journey in Canada. Four months later, it arrived in Mexico.

 The length of the butterflies find their way back to the same place? Another amazing thing is that the butterflies always return to the same area in central Mexico.

 How do the butterflies find their way back to the same place? This is an interesting question because only every fourth generation(代) makes the trip south. In other words, the butterfly that travels to Mexico this year is the great-great-grandchild of the butterfly that traveled there last year.

 Each year, four generations of a Monarch butterfly family are born. Each generation of the family has a very different life. The first generation is born in the south in late April. It slowly moves north, reproduces(繁衍), and then dies. On the trip north,two more generations are born, reproduce, and die. Each of these generations of butterflies is born. This generation has a much longer life. It lives for about eight months. This generation of butterflies makes the amazing journey back to the winter home of its great-great-grandparents. The butterflies spend the winter there, and in the spring they reproduce and then die. Their offspring will be the first generation of the next circle of life.

 Today, people are still studying the Monarch butterfly. But they are not clear about everything.

    Your body is special – no two people in the world are alike, Although you are different from everyone else, you have exactly the same body parts as the people around you, doing different jobs that keep all of us alive.
    What is inside my head ?
    Your head houses the most valuable part of your body – your brain. As you are reading, your eyes send pictures to your brain which makes meaning from what you see. Your brain helps you to remember and think, and makes sure your body is doing what it should.
    What is my skin(皮肤) for ?
    Your skin covers your body. In most parts of your body, the skin is just as thick as half a centimeter. If you have your skin cut, it will have a quick cure and stop viruses from getting into your body. Your skin also helps you feel the heat and coldness of the environment around you. Hair grows from inside the skin. When you feel hot, extra heat comes out through your skin. As a result, your body temperature drops.
    How do I move ?
    Muscles(肌肉) are found in most parts of your body. They work with your bones to help you move – whenever you cry or smile, eat or speak, walk or dance, etc.
    Why do I breathe ?
    Your body needs to take in oxygen from the air and give out the unwanted carbon dioxide in the body. When you breathe, air comes through your nose and mouth into your lungs(肺) where oxygen flows to different parts of your body.
    What makes me sneeze ?
    When dust or a strong smell gets into your nose, you sneeze. This is the way your body cleans up the dust in your nose. Your lungs push out the air and try to clear your nose.
    What does my heart do ?
    Your heart is a very special muscle. It is slightly bigger than your fist (拳头) and grows bigger as you do. If you place your hand on your heart, you will feel your heart beating which forces blood to move around your body.

    The world is not hungry，but it is thirsty. It seems strange that nearly 3/4 of the earth is covered with water while we say we are short of (短缺) water. Why? Because about 97% of water on the earth is sea water which we can't drink or use for watering plants directly. Man can only drink and use the 3%—— the water that comes from rivers and lakes. And we can't even use all of that， because some of it has been polluted.

     Now more water is needed. The problem is: Can we avoid a serious water shortage (短缺) later on?

     First we should all learn how to save water. Secondly，we should find out the ways to reuse it. Scientists have always been making studies in the field. Today，in most large cities water is used only once and then runs to the sea or rivers. But it can be used again. Even if every large city reused its water，still there would not be enough. What could people turn to next?

     The sea seems to have the best answer. There is a lot of water in the sea. All that needs to be done is to get the salt out of the sea water. This is expensive， but it's already used in many parts of the world. Scientists are trying to find a cheaper way of doing it. So you see，if we can find a way out，we'll be in no danger of drying up.

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

    What do you usually do on your smartphone? Send text messages, make phone calls or play video games? Now, thanks to a beginner-friendly programming（程序设计） tool, kids can do more than just play games on their smartphones-they can make their own games.

    US high school student Samuel Ndungi spent a few months learning how to make apps（应用软件）for smart-phones.

    "I was really shocked that you could do this on your own," Ndungi said "I thought only people from Microsoft and big companies could do this."

    Ndungi took a class run by his teacher, Michael Braun. In Braun's class, kids learned how to use the beginner-friendly programming tool to program their own mobile apps.

    This tool is called TouchDevelop. It puts basic instructions（基本指令） into blocks of code（代码）, and kids can put them together like Legos to run games, stories and other apps.

    With TouchDevelop, student Tony Huynh learned how to make his own games. "You get to put your own thoughts into the game, like the animals you want, the kinds of backgrounds you would like to see, and so on," he said.

    Another student Shina Williams wrote a program with about 80 lines of code that paints a picture of his childhood Teddy Bear." It's your own creativity, your own mark（印记） of something that's put in there and it stays in there, " she said.

    Coding is more than just a job skill. Children who learn coding also find new ways to think, create and express themselves.

    We are lucky to live in a rich country where we have many things. However, most of us usually {#blank#}1{#/blank#} (waste) some things.

    Electricity is one thing that we waste most. Lights, TVs, {#blank#}2{#/blank#} (radio) and other things are often kept on even when no one is using them. We should turn them off {#blank#}3{#/blank#} we do not need them. It takes  {#blank#}4{#/blank#} (little) than a second to do it. Anyhow, not wasting electricity saves money, because we do not have to pay for the electricity we do not use. The {#blank#}5{#/blank#} (two) thing that we often waste is water. Fresh water is precious, so it shouldn't be wasted. It is only a simple matter of turning {#blank#}6{#/blank#}a tap. I am sure everybody can do this {#blank#}7{#/blank#} (easy) if he wants to. Another big waste is food. My mother used to cook so much food that much of it was thrown away. I told her we had wasted so much {#blank#}8{#/blank#} (food). She thought I was right and now cooks mainly what we can eat.

    It is not right to be wasteful. I find there is a simple way of not wasting things. That is {#blank#}9{#/blank#} (use) only what we need. Do not touch what we do not need. {#blank#}10{#/blank#}this way, we can stop being wasteful.