A Cloud of Hope and Danger
In 2050, a small cloud floats through the air in a hospital operating room. In the room a patient, suffering from cancer, lies on a table. The cloud surrounds (包围) the patient, (cover) her body and filling her lungs (肺). The cloud is not smoke or steam. It is made of millions of tiny (极小的) robots called nano-robots (纳米机器人). These tiny robots move from cell to cell in the (patient) body, destroying the cancer cells.
Fighting cancer with nano-robots is only an idea today, but scientists say that it would be (impossible) in the future. Using nano-robots for good purposes such as fighting disease or repairing the environment may be the (solve) to many of today's problems.
However, nano-robots could be a (danger) risk as well. Since nano-robots are so tiny, they will have to work in large teams of many thousands to many millions. For this reason, nano-robots will have to be programmed (编程) to build (they). 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 nano-robots would be far (bad) than any disease. Some people think that if they get out of control, nano-robots could destroy the Earth.
What should be done? Should we continue (research) nano-robots or should we search for other methods? This is one of the many difficult (decision) that we have to make in the future.
