Trees are useful in three important{#blank#}1{#/blank#}  .The most important way is that they  provide man with food , wood and other products. Trees provide food not only for man, but also for animals.{#blank#}2{#/blank#}trees, many animals could not live on the earth. It's not {#blank#}3{#/blank#} for man to live on the earth, either.
    The second important way is that trees give us shade(树荫). On a hot summer day, people are eager to have a rest under the shade of a tree after{#blank#}4{#/blank#}a long way. You can imagine how important the shade of a tree is to man and animals.
    The third important way is that trees help to{#blank#}5{#/blank#} droughts and flood. However, in many parts of the world, man hasn't realized it. He has cut trees down in large numbers. In the end, he finds that he has lost the best friends he had.

                                                                             Twenty-First Century Books

      Probably you have seen someone reading a book on an electronic reading device. Over the past few years, these small computers have become more popular. For that reason, more companies that make  {#blank#}1{#/blank#}   paper books are now making electronic books (ebooks). Most ebooks are the same as paper books,   {#blank#}2{#/blank#}  people download a file into a reading device rather than   {#blank#}3{#/blank#}  the paper book. This way they can  {#blank#}4{#/blank#}   many books.
      Books companies are adding special features   {#blank#}5{#/blank#}   some ebooks. These extra features might include sound files, picture files, or video files. When the readers click on these files they learn more about the book, the story, or the writer.
    The latest electronic readers are smaller and   {#blank#}6{#/blank#} , but they are also much more powerful. They can store much more information, so writers and book companies can do more with   {#blank#}7{#/blank#}   ebooks. They do not want to just add files to   {#blank#}8{#/blank#}   completed book. They are making the sound, picture, and video files part of the story. Readers need these files to understand the whole story. Readers can {#blank#}9{#/blank#} change the story.
    Readers already have a lot of books to choose from. If they can change the way stories end, they will have more {#blank#}10{#/blank#}  !

    Children grow quickly, especially their feet. But many families, cannot a{#blank#}1{#/blank#} new shoes when a child needs them. As a result, about 300 million children around the world go barefoot. Those children risk picking up diseases and parasites（寄生虫）from the soil.

    An American man has a s{#blank#}2{#/blank#}． for those barefoot kids – a shoe that grows with the child. Kenton Lee is the creator of The Shoe That Grows. He explains how the shoe works and how it is able to last so long.

     “It grows in three places: the front, the side and the back with the child. It can last up to five years. The b{#blank#}3{#/blank#} is compressed（压缩的）rubber like tire rubber. The top is just high-quality leather.”

    The shoe comes in two sizes: small that fits children aged 4 to 9 and large for children aged 9 to 14. Lee says he got the idea for the shoe while working as a v{#blank#}4{#/blank#} in an orphanage in Kenya. “… and there was a little girl in a white dress walking next to me. And I just remember looking down and seeing how small her shoes were. And she had to c{#blank#}5{#/blank#} open the front of her shoes to let her toes（脚趾）stick out. At that time I just remember thinking, wouldn't it be nice if there were a pair of shoes that could grow with her feet?” However, Lee says it was i{#blank#}6{#/blank#} to turn his idea into a reality at that time. “Yet I kept writing down I should do this because of this or because of that. All these reasons why it really was important for me to try to make the shoes grow are to try to help them.” Finally, in 2009 Lee founded a non-profit organization called Because International. Together, they have sent over 50,000 pairs of shoes to 70 countries. Lee says a pair shoes gives a child self-worth and more chances to succeed b{#blank#}7{#/blank#} much protection.