A Cloud of Hope and Danger

    In 2050, a small cloud floats through the air in a hospital operating room (手术室). In the room a patient, suffering from cancer, lies on a table. The cloud surrounds (包围) the patient, {#blank#}1{#/blank#} her body and filling her lungs (肺). The cloud is not smoke or steam. It is made of millions of microscopic robots {#blank#}2{#/blank#} nano-robots (纳米机器人). These tiny robots move from cell (细胞) to cell in the patients' body, destroying the cancer cells.

    Fighting cancer with nano-robots is only an idea today, {#blank#}3{#/blank#} scientists say that it would be possible in the future. Using nano-robots for good purposes such as fighting disease or repairing the environment may be the {#blank#}4{#/blank#} to many of today's problems.

    However, nano-robots could be a {#blank#}5{#/blank#} risk as well. Since nano-robots are so tiny, they will have to work in large teams of many thousands to 'many millions. {#blank#}6{#/blank#} this reason, nano robots will have to be programmed to build {#blank#}7{#/blank#}. Scientists will not have the ability to build millions of nano-robots one by one.

    This ability to reproduce (复制) is making some scientists worried. What if something goes wrong in the programming? Quite a lot of crazy nan-orobots would be far {#blank#}8{#/blank#} than any disease. Some people think that if they get out of control, nan-orobots could destroy the Earth.

    What should be done? Should we continue {#blank#}9{#/blank#} nan-orobots or should we search for other methods? This is one of the many difficult {#blank#}10{#/blank#} that we have to make in the future.

    Every morning my father buys a newspaper on his way to work. Every evening my mother reads magazines at home. And every night, I look at the posters with photos of David Beckham and Yao Ming on my bedroom wall before I go to sleep. Can we{#blank#}1{#/blank#}life without paper or print?

    Paper was first created about 2,000 years ago, and has been made from silk, cotton, bamboo, and since the 19th century, from wood. People learned to write words on paper to make a book. But in those days, books could{#blank#}2{#/blank#}be produced one at a time by hand and they were expensive and rare. Because there weren't many books, few people learned to read.

    Then printing was invented in China. When printing was developed greatly at the beginning of the 11th century, books could be produced more quickly and cheaply. Then more people learned to read. After that, knowledge and{#blank#}3{#/blank#}spread quickly.

    Today information can be received online, downloaded from the Internet rather than found in books, and information can be kept on CD-ROMs or machines,{#blank#}4{#/blank#}MP3 players.

    Computers are already used in classrooms, and newspapers and magazines can already be read online. So will books be replaced by computers one day? I am not sure.