In the story of “The crow and the Pitcher” from Aesop's Fables, a thirsty crow(乌鸦) drops stones into a narrow jar to raise the low level of water inside so he can take a drink.

    Now scientists have evidence to back up that story. New Caledonian crows actually do understand how to make water displacement work to their advantage, experiments showed. The results suggest that the birds are, at least in some aspects, as smart as first-graders, according to the study.

    Researchers, led by Sarah Jelbert at the university of Auckland in New Zealand, presented six crows with tubes filled with water. Inside the tubes, a worm or piece of meat on a piece of wood was floating, just out of reach of the crow. In front of the tubes, the researchers arranged a bunch of heavy rubber erasers that would sink, and light plastic objects that would float. The crows found out that they could drop the heavy objects into the tubes in order to raise the water level and get their snack.

    However, the birds handled awkwardly in experiments in which they could choose to drop objects in either a wide tube or a narrow tube to get a snack, the researchers said. Dropping objects into narrow tube would lift the water level by a greater amount and put the treat within reach after just two drops. In contrast, it took around seven drops to raise the snack to the same level in the wide tube. The crows obviously didn't realize this, and most of them went for the wide tube first.

    Previous studies showed that chimps and human children can solve similar tasks. In a 2011 study, chimps and kids found out that they could put water into a tube to reach a peanut that was floating in small amount of water at the bottom.

    I went through a training program and became a literacy volunteer(扫盲志愿者)last summer. The training I received, though excellent, did not tell me how it was to work with a real student. When I began to discover what other people's lives were like because they could not read, I realized the true importance of reading.

    My first student Marie was a 44-year-old single mother of three. In the first lesson, I found out she walked two miles to the nearest supermarket twice a week because she didn't know which bus to take. When I told her I would get her a bus schedule, she told me it would not help because she could not read it. She said she also had difficulty once she got to the supermarket because she couldn't always remember what she needed. Since she did not know words, she could not write out a shopping list. Also, she could only recognize items by sight, so if the product had a different label(标识), she would not recognize it as the product she wanted.

    As we worked together, learning how to read built Marie's self-confidence, which encouraged her to continue her studies. She began to make rapid progress and was even able to take the bus to the supermarket. After this successful trip, she reported how self-confident she felt. At the end of the program, she began helping her youngest son, Tony, a shy first grader, with his reading. As she described this experience, I was proud of myself as well. I found that helping Marie to build herself-confidence was more rewarding than anything I had ever done before.

    As a literacy volunteer, I learned a great deal about teaching and helping others. In fact, I may have learned more from the experience than Marie did.

    An autonomous vehicle designed for making local commerce deliveries was unveiled by Nuro. The vehicle is about the height of an SW but far narrower than a typical car. The electric car features four exterior compartments (暗格) — two on each side — to hold separate deliveries. Each compartment can be tailored to a specific use, such as cooking a pizza or refrigerating a package.

    “We can use self-driving technology to deliver anything, anytime, anywhere for basically all local goods and services,” Nuro co-founder Dave Ferguson said. “Consumers used to be okay with two-week paid shipping. It became two-week free delivery, followed by one week, two days, and the same day. Now same-day delivery isn't fast enough for some customers.”

    Nuro isn't alone in building robots for local commerce deliveries. Earlier this month, Toyota, a Japanese car company, unveiled a concept vehicle that could be used for package delivery. A handful of startups — including Starship Technologies, Marble and Dispatch — are testing small robots for deliveries on sidewalks.

    Nuro's vehicle will likely face legal hurdles. Fully autonomous vehicles without a test driver aren't legal in California today, and many companies have shifted testing to states where regulators are more welcoming of autonomous vehicles, such as Arizona.

    Nuro expects to face fewer challenges because it doesn't carry passengers. Nuro's narrow size may also be helpful when navigating streets and avoiding pedestrians. The vehicle isn't equipped with any special features to communicate with pedestrians or other road users. Some companies have tested and patented solutions such as digital screens that signal the car's next move. Ferguson said his team conducted studies and found that such techniques could confuse people. Nuro believes it's better to make sure the car performs predictably, so that human drivers know what to expect from it.

    “We feel by creating this new technology that's going to enable this last mile delivery, we're going to be creating new markets and doing things that previously weren't possible,” Ferguson said. “This is not swapping out Jobs with robots. It's creating new markets. There will definitely be new employment opportunities.”

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A lot of people admired our neighbor. One day a delivery truck unloaded a large 1 system at their house. And the kids discussed the new sound equipment my neighbor had just bought. Meantime, we were living in a house decorated 2 and dressing our kids in second-hand clothes. We lived a 3 life. 

My poor mother-in-law, in town for a visit, got to hear my complaints that night. "I feel so 4 sometimes," I told her, as we 5 the table after dinner. "I know we're doing the right thing, living frugally (节俭的), saving money, but it feels so hard. There're so many things I'd like to 6 , so many things I'd like to do, but we just can't."

She 7 as she folded a cloth napkin in silence. Then she turned to me and said, "When you make a comparison between yourself and others, it's easy to 8 what you don't have. But there's one thing you two do that many other couples may 9 to do. You two often go out together and take time to focus on your 10 . And that's a very important thing."

I stopped wiping the table and 11 for a minute. I thought of the movie my husband and I had seen a week earlier. I 12 the bike rides, the hikes and the picnics. Most of all, I remembered how 13 we were together, even after twenty years. How many people can say that? 

I looked around my home in a new 14 . Our refrigerator was too small for a family of six, but it was 15 filled with delicious food. Our kitchen was small and we had no big TV, but we're happy! And that's enough!