Mrs. White lived in a town of England. Her husband died three years ago and one of her children worked in the capital and the other three lived in another town. Her husband didn't leave her much money and she had to live a simple (简朴) life. Sometimes her children went to see her during their holidays, but they stayed with her for only two or three days.

    One winter morning the old woman got up early. She was going to buy some food in a shop. And when she came out, she found there was much snow in the street. She had to sweep it away. And suddenly she found a dying dog at the comer of the house. She picked it up and took it into the house quickly. She put it near the fire and gave it some milk and bread. At first the poor dog ate nothing and that afternoon it drank some milk and three days later it was all right. Now the old woman found it was a beautiful dog. And she liked it very much and took it everywhere she went. A week later she went shopping with her dog. At a bus stop a young man was eating fish and chips. The little dog became very excited at the smell of the man's lunch and began jumping up at him.

    “Do you mind if I throw it a bit?'' asked the young man.

    “Not at all,” answered Mrs. White.

    Having heard this, he picked up the dog and threw it over the wall.

    Not long ago, I tried convincing my three daughters that the world's secrets are hidden inside silence. The girls looked at me skeptically. Surely silence is nothing?

    Sitting there at the dinner table, I suddenly remembered their curiosity as children, their wondering about what might be hiding behind a door and their amazement as they stared at a light switch and asked me to “open the light”. But now they are 13, 16 and 19 and wonder less and less. If they still wonder at anything, they quickly pull out their smart phones to find the answer. None of them have any interest in discussing with me. To attract their attention, I told them about two friends of mine who had decided to climb Mount Qomolangma.

    Early one morning they left base camp to climb the south-west wall of the mountain. It was going well. Both reached the summit, but then came the storm. They soon realized they would not make it down alive. The first got hold of his pregnant wife by satellite phone. Together they decided on the name of the child that she was carrying. Then he quietly passed away just below the summit. My other friend was not able to contact anyone before he died. No one knows exactly what happened on the mountain in those hours. Thanks to the dry, cool climate 8km above sea level, they have both been freeze-dried. They lie there in silence, looking no different.

    The girls remained quiet, listening. It seemed as though they had got something.

    It is easy to assume that the essence (本质) of technology is technology itself, but that is wrong. The essence is the time we spend with our family and how much freedom we have by technology.

    Dutch beachcomber (海滩拾荒者) Wim Kruiswijk has accumulated a collection of 1,200 messages-in-bottles over the course of nearly 4 decades and has responded to almost all of them,

    68-year-old Kruiswijk says that his unusual hobby began in 1983 when he found three drift bottles (漂流瓶) on his local beach, each containing letters and return addresses. He wrote to all three addresses and was surprised to receive responses from each one. It was this experience that aroused his interest in hunting and collecting messages in bottles, and he hasn't stopped looking for them since.

"I find my messages in bottles on the beach of Zandvoort, where I live, and on the Dutch Islands," Kruiswijk recently told Great Big Story. "Messages in bottles is slow mail. It takes you days, or weeks, or months to find a bottle. "

In the early years, Kruiswijk would find as many as 50 bottles a year, but since 2000 that has slowed to around 20-30 finds, mainly due to beach cleaning efforts. He believes that the rise of the Internet has also played a role in the diminishing number of messages in bottles, telling Dutch newssite PZC, "I used to get a response at half the bottle messages that I answered. Now that's less; many people want 'instant satisfaction'."

    Throwing a message in a bottle out into the sea is a longstanding human tradition dating back to the time of the Greek philosopher Theophrastus, about 310 BC，who used the bottles to study water currents. Scientists still apply the method to this day, as a means to help researchers develop ocean circulation maps, and to crowdsource scientific studies of ocean currents.

    In the past bottles have also been used to send distress messages from sailors in trouble. They also have been used for memorial tributes, or to send loved ones' ashes on a final journey. One of the more common uses though is just to send invitations out to prospective pen pals, a quaint notion in these modern times, but, as Kruiswijk so clearly shows, an effective one.

    Drug companies have spent billions of dollars searching for therapies to reverse or significantly slow Alzheimer's disease, but in vain. Some researchers argue that the best way to make progress is to create better animal models for research, and several teams are now developing mice that more closely imitate how the disease destroys people's brains.

    The US National Institutes of Health (NIH), the UK Dementia Research Institute and Jackson Laboratory (JAX) - one of the world's biggest suppliers of lab mice - are among the groups trying to genetically design more suitable mice. Scientists are also exploring the complex web of mutations(突变) that influences neurological (神经学的) decline in mice and people.

    "We appreciate that the models we had were insufficient. I think it's sort of at a critical moment right now." says Bruce Lamb, a neuro-scientist at Indiana University ~ho directs the NIH-funded programme.

    Alzheimer's is marked by cognitive impairment(认知损伤) and the build-up of amyloid-protein plaques (淀粉样蛋白块) in the brains of people, but the disease does not occur naturally in mice. Scientists get around this by studying mice that have been genetically modified to produce high levels of human amyloid protein. These mice develop plaques in their brains, but they still do not display the memory problems seen in people.

    Many experimental drugs that have successfully removed plaques from mouse brains have not lessened the symptoms of Alzheimer's disease in people. One focused stumble came last month, when three companies reported that their Alzheimer's drugs had failed in large, late-stage clinical trials. Although the drugs successfully blocked the accumulation of amyloid protein in mice, they seemed to worsen cognitive decline and brain shrinkage in people.

    The drive for better mouse models comes as genomics studies are linking the most common form of Alzheimer's to dozens of different genes. This diversity suggests that each case of the disease is caused by a different combination of genetic and environmental factors. "There is no single Alzheimer's disease," says Gareth Howell, a neuro-scientist at Jackson Laboratory (JAX) in Bar Harbor, Maine.

    Howell argues that scientists' reliance on lab mice with only a few genetically engineered mutations might have limited research. His own work suggests that in mice, just as in people, genetic diversity plays a part in determining how Alzheimer's develops.

    China has become the first country to successfully land a spacecraft on the far side of the moon. The Chang'e-4 probe (探测器) has also made the first lunar landing since 1972. It has the task of exploring the side of the moon that never faces the earth. The dark side of the moon is older and has a thicker surface than the visible side. It takes the moon as long to go around on its own axis (轴) as it does for one complete orbit around the Earth.

    The Chinese probe landed in a huge crater 2500 km in diameter and 13 km deep. The crater is one of the oldest parts of the moon and our solar system.

    Scientists hope to learn more about the geology of the far side of the moon. The craft has two cameras on board which will send images back to earth. It will also attempt to send signals to distant regions of space, something that cannot happen on earth because of too much radio noise.

    Chang'e-4 also has instruments on board to examine minerals as well as a container with seeds which will try to create a miniature (微型的) biosphere (生物圈).

Communication with the spacecraft is not easy. Images and other data must be transmitted to a separate satellite because no direct communication with the earth is possible.

    For China the Chang'e-4 mission is an important achievement, because the country has successfully done something no other nation on earth has. It wants to become a leading power in space exploration and has announced plans to send astronauts to the moon and set up its own space station.

    Ride-hailing apps and robot cars promise to change how we get around and the effects are already being felt. Traffic in New York is slowing down. Jams are common in Manhattan, especially in its business districts. Daytime traffic in the busiest areas now moves almost 20% more slowly than it did five years ago.

    It seems a place ripe for wide use of ride-hailing apps that, you might think, would reduce some of the jams. However, those apps appear to be making things worse as traffic has slowed in line with the growing popularity of apps such as Uber and Lyft, a study by transport expert Bruce Schaller suggests.

    Over the four years of the study, the number of cars in Manhattan seeking ride-hailing fares increased by 81%. There are now about 68, 000 ride-sharing drivers across New York. That's about five times the number of the yellow cabs licensed to operate there, he found. There are so many drivers, his work suggests, who spend about 45% of their spare time just touring for fares. That is a lot of unused cars blocking a lot of busy streets.

    Simple physics explains why ride-sharing vehicles are causing, not curing jams, said Jarrett Walker, a public transport policy expert who has advised hundreds of cities about moving people.

    "Lots of people are deciding that, 'Oh, public transport is just too much trouble this morning,' or whenever, which causes a shift from it," he told the BBC. "That means moving people from larger vehicles into smaller ones, which means more vehicles to move the same people. Therefore, more traffic."

    Data gathered about ride-sharing drivers illustrates how they contribute to congestion (塞车), said Prof. Christo Wilson, a computer scientist at Northeastern University who has studied the services. "You can look at the traffic pattern for the Uber vehicles and it perfectly matches the peaks for the rush hour and the peak time of a day," he said. They are out there in force at the worst possible times.