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.

    At 9 a.m., pet owners start to arrive with their sick pets. Appointments take up the whole morning. At midday, I stop for two hours. I don't examine any new sick animals. I use these two hours to{#blank#}1{#/blank#}and do all my paperwork. At 2 p.m., I start to see sick animals again. At 5 p.m., three students from a local school who love animals arrive to help out. They are very{#blank#}2{#/blank#}and warm-hearted. I am always happy to see their smiling faces!

    From5 p.m. to 7 p.m., I continue to see sick animals. Then, at 7 p.m. we close our doors and the clean-up begins! We tidy the clinic and{#blank#}3{#/blank#}and clean the animals. Of course, we also stroke(轻抚) them and give them hugs! Then, we turn off the lights and go home. This is the type of the day I want to have.

    I am very happy being a vet, though unexpected things sometimes{#blank#}4{#/blank#}!