Today, the world's diversity (多样性) of food crops is quickly decreasing. But scientists around the world are taking action. They are building seed banks. At seed banks, scientists store the seeds of many different crops.

    There are now 1,400 seed banks around the world. However, some banks are in warm countries. If the electricity fails, the seeds will get too hot and die. Other seed banks are in countries troubled by war. Sometimes people damage the seed banks. If this happens, valuable seeds can be lost forever!

    The organization Global Crop Diversity Trust decided they wanted to deal with this problem. So, they decided to build a global seed bank. This seed bank would contain a back-up, or extra copy, of all the world's seeds. Smaller seed banks would still collect and keep local seeds. But they would also send copies of their seeds to the global bank.

    Scientists from the Global Crop Diversity Trust chose the cold, snowy mountains of Svalbard, Norway to build the global seed bank — the Svalbard Global Seed Vault (斯瓦尔巴全球种子库). Organizations, farmers, or local seed banks store their extra seeds there. And the people who place their seeds in the vault are the only people who can take them out. They pay to ship their seeds to Norway, but it does not cost them any money to store their seeds. The Global Crop Diversity Trust pays for this.

    Cary Fowler is a scientist who heads the Global Crop Diversity Trust. He said, “If the Seed Vault simply supplies seed banks with copies of seeds that those banks lost by accident, the Seed Vault will be worth more than it cost.”

    Elephants might be the most well-known and well-loved animal in African wildlife. But conservation (保护) of the African elephant faces special difficulties. While the elephant population is half of what it was 40 years ago, some areas of Africa have more elephants than populated areas can support. That's why AWF scientists are studying elephant behavior, protecting habitats and finding ways for humans to live peacefully with elephants in Africa.

    Years ago, over hunting and the ivory trade were the biggest threats to elephants survival. Luckily, ivory bans (禁令), hunting rules and protected areas protect elephants from these dangers today.

    The 21st century brings a different challenge to elephant conservation —land-use. Elephants walk across borders and outside parks and other protected areas. So they often destroy crops, causing conflicts (冲突) between local farmers and these big animals.

    Successful conservation strategies (策略) must allow elephants to walk freely in their natural habitats while reducing conflicts between elephants and local people.

    AWF researchers are searching for a way to give both elephants and people the space they need. The AWF is collecting information on elephant habitats and behavior. The information they gather will help to develop the widest possible space for elephants.

    The AWF is helping elephants by protecting their habitats. And they also work with local farmers to improve their life in order to encourage them to protect rather than destroy elephants.

    Winslow Homer was a famous American painter. Since Art History class in college, I had always admired his works and I was lucky to see a large exhibition of his works when I was in my early 30s. It was at this event that I bought a print of his painting. “Snap the Whip.” I had it framed and until I retired from teaching it always hung in my classroom

    I thought it truly captured(捕捉) the freedom and fun of childhood. In the painting, a group of young boys are playing a game arm in arm on grass ground in front of a farm house. They are jumping and laughing wildly with great joy. One of the boys is falling down to the ground. They are not even wearing shoes!

    During my last year of teaching, there was a young woman in her first year of teaching right next door to me and we got to be good friends. She had been an art student before taking up education. Her eyes were drawn immediately to this print when she entered my room. So on my last day of teaching, after the students had left, I took the painting off the wall and walked next door and gave it to her.

    She was really surprised, but very pleased to have it. I was pleased that she liked it and all the students she would have would treasure(珍爱) it as much as I had. We found the perfect place for it on one of her walls and hung it together. Thank you for bring back this wonderful memory for me.

    London's transport services offer you a special experience of the city. Here's a round-up of the transport choices available to you.

    London Underground

    There are 11 colour-coded Underground lines. Services run regularly from around 05:00 to 00:30 (Sunday 07:30 to 23:30) on most routes.

Visit tfl.gov.uk/tube for more information.

    Tip:

    Always stand on the right when using the escalators (电动扶梯) at Tube stations. It can get hot and busy on the Tube during peak (高峰) travel times, so you may prefer to travel outside these hours.

    Buses

    A cheap and easy way to travel around London. They generally run from 05:00 to 00:30. Night buses operate on many major routes from around midnight to 05:00, and some operate a 24-hour service.

    It is not possible to pay for your London bus fare in cash. Instead you can pay with a Visitor Oyster card, Oyster card, Travelcard or UK-issued contactless payment card. A single bus journey is £1.50 with an Oyster card or UK-issued contactless payment card.

    To help you get home, if you don't have enough credit on your Oyster card, you will be able to make one more bus journey.

    After this you will need to top up the credit on your card before you use it again. If your contactless payment card has been issued outside the UK, please check tfl.gov.uk/contactless before you use your card to travel on our bus services. For any international transaction fees (手续费) that may apply, please check with your card issuer.

    For more information visit tfl.gov.uk/buses.

    Tip:

    Some bus routes are especially good for sightseeing — try routes 9, 14, 15 and 22. The New Routemaster bus featured in the James Bond film Skyfall and runs on routes 9, 11, 24, 38 and 390.

    If you run out of credit on your Visitor Oyster card, it's easy to add more at:

    Touchscreen ticket machines in Tube, DLR, London Overground and some National Rail stations.

    Around 4,000 Oyster Ticket Stops cross London (Find your nearest one at ticketstoplocator.tfl.gov.uk).

    Travel & Visitor Information Centres.

    London Overground station ticket offices.

    Even for a first-time visitor to China, it is impossible to ignore the popularity of Quick-Response (QR) codes. These square-shaped black-and-white symbols in WeChat or Alipay where QR codes are scanned to add new friends or make payments.

    The QR Code system originated in Japan. The engineer Masahiro Hara felt the limitation of the one-dimension barcode in use and thus developed the QR codes which could carry data horizontally and vertically. QR codes could hold much more information than barcode due to their extra dimension. In addition, QR codes have larger data capacity, smaller print—out size and higher resistance to dirt and damage, which make them widely applied in many other applications.

    Though the technology of QR codes is complicated, we can easily create our own QR codes with the help of QR code generators, many of which are available online for free. Users could enter the data they wish the QR code to display, and the generator turns it into a symbol that can be printed or displayed in electronic form. The process of creating QR codes could be really fun when we customise the design of the codes according to our specific needs. For instance, we can adjust the color, add a logo, and create social options etc. Moreover, dynamic (动态的) QR codes are also available. They are more various than standard QR codes because they allow users to edit data entered previously whereas data in standard QR codes cannot be edited once printed. Plus, don't limit your QR code to one mobile scanner. Anyone can scan your code with any reader. A lower barrier to entry makes success more likely for you and the user.

    Meanwhile, we must also recognize the vulnerability of QR codes. Due to its easy access, criminals can steal simply by replacing the QR codes with their own, routing cash into their own bank accounts. Hence, we should all become more conscious towards virtual money transactions through QR codes and participate in additional security measures.

    When French students go to school, they have to leave one of their most prized possessions at home — their smartphones. French lawmakers passed a law on July 31, 2018, banning students 15 and under from bringing smartphones and tablets to school, or at least requiring they be turned off at school. Officials in support of the new rule described the policy as a way to protect children from addictive habits and to safeguard the sanctity of the classroom.

    "We know there is a phenomenon of screen addiction," education minister Jean-Michel Blanquer said. "Our main role is to protect students. It is a fundamental role of education, and this law allows it."

    The law, however, makes exceptions for educational use, after-school activities and for students with disabilities. French high schools can choose to force a less-strict ban on Internet- connected devices.

    Even before the new policy was voted in, French law carried out in 2010 prohibited students from using their phones while class was in session. But during the 2017 French presidential election, Emmanuel Macron promised to force a school ban on phones entirely.

    This isn't the first French law designed to beat back the influences of digital technology in everyday life. In 2017 the government passed a law requiring French companies to draft rules that limited work emails and work-related technology outside the office. Referred to as the "right to disconnect," French officials said the law aimed to reduce job-related stress and prevent employee burnout.

    "Employees physically leave the office, but they do not leave their work. They remain attached by a kind of electronic tie," said Benoît Hamon, former French education minister. "The texts, the messages, the emails: they control the life of the individual to the point where he or she eventually breaks down."