When you hear about trees cut for paper, you might think of your favorite trees in the backyard, nearby parks or wild forests being cut to pieces.

 The good news is that production and use of paper will not cause forests to disappear. Most trees used for paper come from timberlands(林地). People plant trees here for use. It usually takes 10 to 20 years for trees to grow big enough to be cut down. During that time, trees provide a home for animals and produce oxygen(氧气) for the earth. And after people cut down the big trees, they plant small ones again.

 Often, a tree is not cut down for making paper at all. People use the big part for buildings. Paper is then made from the left small part.

 We also recycle paper—People collect used paper and turn it into new products, likes boxes, newsprint and writing paper, in the factory. So it's important for us to recycle paper and reduce(减少) the amount(数量) of it in landfills(垃圾处理场).

    Have you learned something about robots? There are all kinds of robots. They are in different shapes. They can do lots of work.

    Robot teachers， who are working in elementary schools now， have been very popular with pupils during a project in some South Korean school， a government report said on Thursday.

    The elementary school children get on well with the robot teachers. They like the robotic teachers more than the ordinary ones because they never get angry and always kind to the students. The Ministry of Knowledge said.

    English teaching robots were sent to three provincial schools for eight weeks starting in late December. There they teach students as teachers. More and more students like studying and the other robot teachers were also sent out. They can teach math， science and art.

    The researchers found that the English-teaching robots helped raise interest in the language and helped the students feel more confident.

    “Tele-presence” robots are controlled by an English and are equipped with a microphone and video camera. Many people think we can use these robot teachers in the village far away from the cities so that the children in these areas can also get better education.

    The government has expressed great interest in robots to give rural school children more learning chances. I think in the future we can see more and more robot teachers working with the students. But I think the robot teachers can't replace the real teachers. What's your opinion?

    Chinese companies lead in global 5G patent applications(专利应用) with Huawei taking the crown, according to a report by IPlytics, an authorized patent data company. Three companies from China were included in the top 10 list of 5G Standards﹣Essential Patents(SEPs)family owner. Huawei ranked first. ZET Corp, and China Academy of Telecommunications Technology (CATT)grabbed fifth and ninth places, respectively.

    Chinese companies topped the list for most 5G SEPs applications in communication systems by the end of April 2019, accounting for 34 percent of the world's total. Chinese tech giant Huawei has taken a leading role by owning 15 percent of SEPs, according to the report Who Is Leading the 5G Patent Race？

    5G SEP are patents that any company will have to use when carrying out 5G technology and no one can avoid them.

    Different from 3G and 4G technologies, 5G technology will influence various industries and encourage the appearance of many new products, services and industries.

    The automotive sector will most likely be one of the first industries to depend on 5G, which will connect vehicles to other vehicles, roadsides, traffic lights, buildings and the Internet, according to the report.

    "It is 5G that is going to be a huge jump forward for communication systems because only with 5G's higher bandwidth can a number of applications be more advanced (尖端的) and used by most consumers," said Nicole Peng, senior director of the market research company Canalys.

    As 5G technology has combined various industries and technologies, the number of 5G SEPs rose to more than 60,000 globally by the end of April 2019, the report said.

    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.

    What is the best way to help control air pollution in our towns and cities? Choose public transportation instead of private cars, or reduce the total amount of cars on the street. These can be useful. But here is a more creative way—write a poem.

    "I write in praise of air. I was six or five, when a magician opened my fist(拳头), and I held in my hand the whole of the sky."

    Professor Tony Ryan (the science expert) and Professor Simon Armitage(the words expert), from the University of Sheffield, UK, came up with the idea.

    But in fact, the poem is not the key part. It is the poster that the poem was written on that plays the biggest part. The poster is 10 meters by 20 meters. It is coated with nanoparticles(纳米粒) of titanium dioxide (二氧化钛). It can absorb the waste from around 20 cars each day if you put it by a busy road. The poster is now displayed on one of the University of Sheffield's buildings.

    It doesn't get rid of all the pollutants from traffic, but it will eat up things called nitrogen oxides (氧化氮). These play a part in breathing problems, including asthma(哮喘).

    The technology is cheap. "It would add less than £100 to the cost of a poster and would turn advertisements into catalysts(催化剂) in more ways than one," Ryan told the BBC.

    He's also working on another idea, which is to add the nanoparticles to washing powder, so that your clothes soak up these poisons while you walk along. And you wouldn't be able to see or feel anything different.