How fit are your teeth? Are you lazy about brushing them? Never fear: An inventor is on the case. An electric toothbrush senses how long and how well you brush, and it lets you track your performance on your phone.

    The Kolibree toothbrush was exhibited at the International Consumer Electronics Show in Las Vegas this week. It senses how it is moved and can send the information to an Android phone or iPhone via a Bluetooth wireless connection.

    The toothbrush will be able to teach you to brush right (don't forget the insides of the teeth!) and make sure you're brushing long enough. “It's kind of like having a dentist actually watch your brushing on a day-to-day basis,” says Thomas Serval, the French inventor.

    The toothbrush will also be able to talk to other applications on your phone, so developers could, for instance, create a game controlled by your toothbrush. You could score points for beating monsters among your teeth. “We try to make it smart but also  fun,” Several says.

    Serval says he was inspired by his experience as a father. He would come home from work and ask his kids if they had brushed their teeth. They said “yes,” but Serval would find their toothbrush heads dry. He decided he needed a brush that really told him how well his children brushed.

    The company says the Kolibree will go on sale this summer, for $99 to $199, developing on features. The U.S. is the first target market.

    Serval says that one day, it'll be possible to replace the brush on the handle with a brushing unit that also has a camera. The camera can even examine holes in your teeth while you brush.

阅读下列短文，从每题所给的四个选项 （A 、B 、C  和 D ）中，选出最佳选项。

    My friend Jennie Crossen gave her bone marrow (骨髓) to a 51-year-old woman with leukemia, a woman she has never met.

    At the end of March, the Red Cross called back. Six different blood elements were tested; Jennie matched five completely and was about a 3/4 match of the sixth. So she was the best match.

    In April, Jennie went for a complete physical exam by one of the doctors who would perform the surgery. The doctor had to make sure that it would be no threat to her. The doctor told her that the surgery would entail having two quarts of bone marrow extracted from her hip bones. Jennie would probably be released the same day the surgery took place and should expect to be sore for a couple of months.

    "I didn't think it was that big a deal until I realized I was a match," Jennie said, "There wasn't a question in my head. It didn't seem like something that was going above and beyond."

    Jennie was left with two very small scars on her lower back from the surgery and was given medication to help dull the pain. She still felt a great deal of pressure on her lower back. "Being only 21, I feel like I am not old enough to significantly impact someone's life," Jennie said, "It seems strange to me that I could possibly save this woman's life which was being cut short by cancer."

    Three weeks after the surgery, Jennie received a call from the Red Cross representative who told her the transplant was successful. "I feel good, and I think it will actually work for her," she said, "So many people say they'd only donate if it was for a family member or close friend. This woman is someone's family and someone's friend. Obviously, no one she knows is a match, and the fact that you'd be able to help a perfect stranger is great."

    If you are given only 1 yuan, could you live in a city for one day? It seems this may be a little difficult. But students from Xi'an did it.

    On April 10, more than 60 students from the Middle School Attached to Northwestern Polytechnic University took part in the One Yuan Metropolis Survival. The charitable organization for teenagers called Imperceptible Education held this activity. Students not only have to live, but they also have to deal with a lot of hard tasks. It has happened in eight cities and is going to four others, including Beijing, in June.

    To make money, many students looked for part-time jobs and saw how hard life was. Zhang Queue, 14, asked more than 10 restaurants for a job and finally got one chance. “We were sad when they said no. But gradually (逐渐地), we got used to it,” he said. After being a waiter for an hour, he got 25 yuan.

    Some made use of their talents by singing and dancing in parks or shopping malls. Many people who walked by took notice and helped them. Zhao Jincheng, 14, drew pictures and made paper crafts(手工). “This showed it's important to learn a special skill,” he said.

    Living was hard, but finishing the tasks wasn't any easier. They went to different places to finish tasks in a short time. The most amazing one was when they had to exchange things worth thousands yuan with only a piece of paper in half an hour. “We learned how to persuade others. From a balloon to a cake to a bottle of yogurt (酸乳) … after almost 20 tries, we got an expensive necklace,” he said. They will give all of the money they made to poor schools in Tibet.

    David Lindenmayer of the Australian National University College of Science in Canberra says that older trees play important roles in maintaining landscapes and ecosystems.

    David studies conservation, landscape, ecology and biodiversity at the Australian National University College of Science in Canberra. “Lots of people recognize that as humans get older they tend to have less and less children while trees do it the other way around. What really happens is that the older some of these really big old trees get, the more seeds they produce and the more germinant（萌芽的）they're likely to be. So it's actually the polar opposite of what we see with humans and most other animals, so really quite extraordinary. “On January 26th he spoke to Scientific American Editor in Chief Mariette DiChristina when they were both at the World Economic Forum in Davos.

    In actually it's quite a worrying situation, because in plenty of forests and woodland and other ecosystems around the world, populations of large old trees are declining very quickly. And this matters because a lot of biodiversity, a lot of carbon, a lot of key ecosystem processes are associated with those really big, old trees.

    We can make sure we grow more forests, that we protect the big trees we have now, and that we don't do things that really put a lot of pressure on those trees. We should not be cutting down really big old trees anymore.

    International Airport Sheremetyevo Moscow

    If You've Lost Personal possessions

    On Board

    Contact the airline's representatives

    At the Airport

    Contact:

    Sheremetyevo Police Department

    +7(495)578-22-55

    Unclaimed luggage storage room in Terminal C

    +7(495)578-23-26

    Umclaimed luggage storage room in Terminal D

    +7(499)500-65-52

    (domestic flights)

    +7(495)753-86-41

    (international flights)

    When collecting Lost and Found items, you shall have an identification document, a boarding pass or a ticket, and also to indicate a place where the items were lost and prove they are yours.

    If Your Luggage Is Lost or Damaged

    Before leaving the arrival area, please turn to the Lost and Found counter to file a report. The written claim shall be submitted to the airline company not later than seven days from the time when the luggage was to be collected.

    If your luggage is not found within twenty-one days of the time when the claim was filed, you have the right to claim damages in the amount of not more than 600 rubles per kilogram. Amount refunded (退款) for a hand luggage lost through the fault of an airline is not more than 11,000 rubles regardless of its weight. Amount refunded for damaged luggage is calculated based on the tariffs (关税).

    Keep your flight documents (a ticket, boarding pass, luggage tag, and delayed luggage report filed at the airport) until the end of the procedure for searching for your luggage.

    Current information on luggage-tracing results

    +7(495)578-76-65

    Lost and Found service of Aeroflot Airlines

    +7(495)544-33-25

    (from 9:00 to 20:00)

    +7(495)753-86-41

    (24 hours)

    For further information please contact the airline.

China's Tianwen 1 Mars probe (探测器) conducted its fourth orbital correction on Friday evening, as the spacecraft makes ready for its arrival in orbit around Feb. 10, according to the China National Space Administration.

The name comes from the long poem Tianwen, meaning Heavenly Questions or Questions to Heaven, written by Qu Yuan, one of the greatest poets of ancient China. In Tianwen, this name conveys the Chinese nation's steady effort in pursuing truth and culture of exploring nature and the universe. CNSA also unveiled (发布) the logo of China's planetary exploration missions, featuring the letter C, signifying China, international cooperation and capacity of entering space.

Tianwen I has flown for 197 days and more than 465 million kilometers on its journey to the planet. It is now around 184 million km from Earth and I. I million km from Mars. Depending on the two planets' orbits, Mars is between 55 and 400 million km from Earth. Mars probe Tianwen I is seen in its first selfies in space on Oct. 1, 2020. The administration also published a black-and-white picture of Mars taken by Tianwen I, the first snapshot (抓拍的照片) from the Chinese craft.

Tianwen I, the country's first independent Mars mission, was launched by a Long March 5 heavy-lift carrier rocket on July 23 from the Wenchang Space Launch Center in Hainan province, kicking off the nation's planetary exploration program.

A successful landing would make China only the second nation to place a spacecraft on the Martian planet. China would also be the first to successfully orbit, land and deploy (部署) a vehicle in the same mission. According to experts, searching for signs of life on Mars will be the first and foremost scientific goal. China is open and inclusive in the development of its space technology not least because it believes that the exploration of outer space should help build a community with a shared future for mankind.