Researchers at an American university are working to create special chewing gum （口香糖） to help reduce the spread of the COVID-19.

Experts agree that vaccination （接种疫苗） is _______   of all the ways to fight against the COVID-19, but vaccinated people can still spread it.   So researchers are hoping that their chewing gum will give people _______ useful and low-cost way to prevent the COVID-19 from _______.

“This chewing gum is made _______ a plant. It has a material _______ can kill the virus in the mouth,” Henry Daniel, the leader of the research, explained, “So, the virus can not revive inside the body. ” That’s _______ it is useful to prevent the COVID-19.

The research is still in _______ early periods.   The researchers are planning to carry out a clinical trial （临床试验） in humans to decide whether people can use it _______ and whether it’s effective. If it _______, people can use it in situations where they need to be close to each other, such as teeth cleaning by a doctor.

“We are already using masks and other things to reduce the spread,” Daniel said. “This gum ________ as another tool to win this fight.   I hope we can succeed in this research. ”

Looking back to when I was younger in the 1980s, I can remember dreaming of two inventions that I thought would change my world but were probably not likely to happen in my lifetime. One was a tiny _______ that I could carry around in my pocket and film moments whenever I had the opportunity.   The other was something I could use to see and speak to people miles away.

It is unbelievable that during my adult life these two _______ have become a reality. And not even two separate inventions. Just one phone, small enough to keep in my pocket so that I _______ know it’s there. I can video call or chat to friends and relatives, catch up with the latest news, watch videos of my favourite bands, check the weather forecast or send messages. I can shop as much as I want and even take a course in any subject I want…the _______ goes on.

Along with the Internet, the mobile phone must be the _______ change in technology ever. So why do many of us feel a little _______ how much time we spend on the phone in our lives? It’s puzzling that the opportunities it has offered us for communication seem to have _______ the time we actually spend talking to each other. We are all used to seeing friends and families who are always _______ their screens and taking very little notice of those around them.

The mobile phone is here to stay and we have to find a way of dealing with the problems it might create. I believe these are challenges we have to solve independently rather than _______ something or someone else to come to our rescue. It’s up to use to be careful about the time we spend online and remember that it’s good to talk with those sitting nearby. We can still feel ________ to have such a powerful piece of technology available when we need it.

Have you ever seen a solar panel（太阳能电池板）in your neighbourhood? Solar panels take energy from the sun and turn it into electricity. Over the past ten years, the price of solar panels has gone down greatly. In many parts of the world, solar energy is now the cheapest form of electricity. More and more people have started using solar energy to power their homes.

However, solar panels also have their problems. They stop working at night and on rainy days. Is it possible to make them produce electricity all of the time?

Scientists at Suzhou University, China, have invented a new solar panel now. It can produce electricity not only from solar energy but also from falling rain. When a raindrop falls on the solar panel and then rolls（滚动）down, it creates friction（摩擦力）on the surface of the panel, which can then be turned into electricity.

Sun Baoquan is one of the inventors. “Our new invention can produce electricity in any weather during the day,”he says. “It can even provide electricity at night if there is rain. ”

The solar panel, however, does not make much electricity from falling rain. So Sun Baoquan is still working hard to improve it. The scientist also wants to make more flexible solar panels, which are as soft as clothing. They will be much lighter and provide more electricity.

The field of solar energy is developing fast. Scientists around the world have been improving solar panels. Some have been working on ways to join solar panels and wind power together. Some have been trying to use sunlight to produce liquid and gas fuels（液体和气体燃料）.

Liu Jichen, a student from Tsinghua University, has developed a WeChat mini-program called “Clear Plate”.     26     a meal, users can open the mini-program and take a photo of their     27     plates. Once the image is checked by the AI, users can collect points and use them to buy gifts or meals for children in poor     28     .

“Technology is a good way to     29       the problem of food waste,” Liu thought. He organised a team of twenty members to work on the project. In order to improve the mini-program, the team     30     half a year collecting over 100,000 photos in school dining halls and restaurants.   In 2018, the mini-program was put into use. Soon, it became one of     31     most popular mini-programs in universities across China.

Meanwhile, Liu and his team, together     32     other organizations, started the “Clear Your Plate” campaign in November in the third year of his university. Almost 1.6 million college students were attracted and food waste was     33       by 862 tons. “Through the campaign, we hope to encourage     34     to take action against food waste,” he said.   

Thanks to his great efforts, Liu stood out     35     more than 7,600 people around the world and was rewarded one of the Young Leaders for the SDGs （可持续发展目标） by the UN.