Most of us spend all day at school or work. After a long and busy day, all we want to do is to return to a comfortable home. Smart technology can turn any home into a nicer place to live in.

Smart homes have been around for some time. Scottish company Pico Electronics invented a type of technology called X10 in 1975. It allows household devices （设备）, such as lights and alarms, to communicate with each other by using radio waves.

Of course, 5G network connectivity has made smart homes more convenient. Perhaps the most widespread smart home technology is the voice-activated assistant（语音激活助手）. Google Home allows users to control nearly any device in their home simply by speaking a few words. This is especially convenient for people with physical disabilities, as they can finish tasks without using their hands or walking around the house.

Common household devices can become “smart” as well. For example, a smart rubbish bin can memorize all the things you’ve thrown away and offer you a shopping list online, while a smart fridge can create dinner recipes （菜谱）according to the vegetables that are being kept inside.

But it’s not just about convenience. Smart homes are also good for the environment. By regularly checking your energy use and turning off lights and other devices that you’re not using, smart homes can lower how much electricity you use overall. Using less energy means that we make less pollution. That is good for the environment.

Nano-robots (纳米机器人)

In 2050, a small cloud floats (漂浮) through the air in a hospital room. In the room, a patient experiencing great pain from cancer(癌症), lies on a table. The cloud covers the patient's body and fills her lungs (肺). The cloud is not smoke or steam. It is made of millions of microscopic robots called nano-robots. These tiny robots move from cell (细胞) to cell in the patient's body, killing the cancer cells.

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

However, nano-robots could be a dangerous 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 to build themselves. Scientists will not have the ability to build millions of nano-robots one by one. This ability to reproduce is making some scientists worried. What if something goes wrong in the programming? Quite a lot of crazy nano-robots would be far worse than any disease. Some people think that if they get out of control, nano-robots could kill the world.

What should be done? Should we continue researching nano-robots or should we search for other methods? This is one of the many difficult decisions that we have to make in the future.