Here is a page from a magazine called Future. Read the following information about things that may happen in twenty years.

    Cars will run on solar power (太阳能) and will be much cleaner and safer. For example, if you are too close to another car or if you are driving dangerously, your car will slow down or stop by itself.

    New cities will have to be built in the sea. Some cities on water will have two levels(层). People will live on the upper level, the lower level will be used for traffic, shops and factories.

    Biotechnology(生物技术) will make food better and healthier. Plants without insects or illnesses(病虫害) will be developed. The taste of fruit and vegetables will be better and food will be kept longer.

    Many new ways to cure(治愈) illnesses will be found. People will use products of genetic engineering (基因产品) to cure more illnesses. However, some new illnesses will appear.

    It took 13 years of international effort to map the human biological blueprint of all the genes (基因) that make us different people. The first rough draft (草图) made in 2000. The last of our 23 chromosomes (染色体) was clearly described in 2006. Ever since then, the age of personal genetic testing has been upon us. Since that time, a growing number of private companies have come on the market mostly through the Internet, offering to scan your personal DNA and compare it to some disease markets of the blueprint, called DTC genetic tests.

    But over the last five years the medical world has been discussing excitedly about whether these DTC tests are helpful or harmful, scientifically believable or completely useless. One of the usual criticisms (批评) is that the science is so new that no one really knows yet how to explain the information.

    "At present they largely remain in the period of research studies," notes Dr. Greg Ferro, special advisor to the director of genomic medicine at the US National Human Genome Research Institute. Ferro says there are two reasons." The first is that when they offer a test, are they really checking what they should check? And then the next is that even if it is believable, does what the test is checking really mean anything to your health?"

    Other worries include the privacy of the results and how your personal genetic information might be used by insurance (保险) companies to refuse your insurance or your boss to dismiss you. Or you could learn information with a huge social or personal impact (冲击), such as finding out that genetically you cannot possibly be the father of your child. It can also give you risks that may break your life, such as whether you are at high risk of cancer, Parkinson or other terrible diseases.

    Criticisms over the tests are such that some countries, such as Germany, have banned them. In 2011, some scientists advised the US government that most tests should be done under the guidance of medical professionals (专家). The UK government also expressed its worries about DTC genetic tests and in August 2010 made a set of rules to guide the development of genetic tests.

    In 2011, three medical researchers published a review article in the International Journal of Clinical Practice, saying that such tests offered more risks than benefits. The most important reason is that the tests might create worries or unreal results or drive unnecessary medical treatments. They also noted some of the genetic information the tests are based on at present is far from being perfect.

    There is one thing. We can't see it. Sometimes we can hear it and even feel it. Without(没有) it, all the living things will die. Do you know what it is? Oh, it is air.

    However, what's the air like today?

    In cities, there are too many people and too many cars on the roads. The cars send out (排放) a lot of bad gases(气体) In cities, there are many chemical factories(化工厂). They send out terrible smoke every day. This kind of smoke is very bad for our health. Now the air is becoming worse and worse. Every day, we breathe (呼吸) the bad air in and out. This is very unhealthy for us and it makes us feel sick.

    To keep us healthy, we have to go to the countryside to breathe more fresh air. Or we can go up hills to get more fresh air.