2 . Stare at a blank wall in any room, and you are unlikely to learn much more than the paint color. But a new technology can unnoticeably scan the same surface for shadows and reflections.     1     But they can be got by one tool and analyzed to determine details including how many people are in the room — and what they are doing. This tool could gather information from a partial view of a space. It can spy on activity from around a corner.     2    

As people move around a room, their bodies block a portion of any available light to create subtle and indistinct “soft shadows” on walls.     3     But these faint signals are usually drowned out by the main source of surrounding light. Sharma and other M.I.T. researchers separated that main source of surrounding light by filming a wall in a room as its occupants moved around and averaging the frames over time. Then the researchers removed shadows from furniture or other still objects from the video in real time, only revealing humans’ moving shadows on the wall.

    4     They crouched, jumped or moved around, alone or in pairs, outside the camera’s view. Then the team fed the videos into a machine-learning model to teach it which soft shadow patterns indicated which behavior. The resulting system can automatically analyze footage of a blank wall in any room in real time, determining the number of people and their actions.

    5     It can register only group sizes and activities for which it has been trained, and it requires a high-resolution (清晰度) camera; a standard digital camera creates too much background noise, and smartphone camera results are even worse.

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4 . Once upon a time, there was a king who had twin sons. There was some _______ about which one had been born first. As they grew up, the king sought out a _______ way of choosing one of them as the crown prince.

One day he said, “My sons, the _______ will come when one of you must succeed (继任) me as king. The _______ of power are very heavy. To find out which of you is _______ able to bear them cheerfully, I'm sending you to one of my advisors, who will place equal burdens on your _______. My crown will go to the one who first _______ bearing his burden.”

The brothers _______ together at once. Soon they met a weak and _______ woman struggling under a heavy weight. One of the boys suggested that they stop to help her. The other ________, “We have a burden of our own to worry about. Let’s be on our way.”

So the second son ________ on while the first stayed behind to help the woman. As he continued, the first son found others who needed ________: a blind man who needed assistance to go home and a lost child whom he carried back to her ________ parents.

Eventually he did reach his father’s advisor, ________ his own burden, and went back home with it ________ on his shoulders. When he arrived back at the palace, his brother met him at the gate and greeted him with ________. “I don’t understand, ” the brother said. “I ________ Father the burden was too heavy to carry. How did you ________ it alone?”

The future king replied ________, “I suppose by helping others carry their burdens. I ________ the strength to bear my own.”

5 . During the rosy years of elementary school(小学), I enjoyed sharing my dolls and jokes, which allowed me to keep my high social status. I was the queen of the playground. Then came my tweens and teens, and mean girls and cool kids. They rose in the ranks not by being friendly but by smoking cigarettes, breaking rules and playing jokes on others, among whom I soon found myself.

Popularity is a well-explored subject in social psychology. Mitch Prinstein, a professor of clinical psychology sorts the popular into two categories: the likable and the status seekers. The likables’ plays-well-with-others qualities strengthen schoolyard friendships, jump-start interpersonal skills and, when tapped early, are employed ever after in life and work. Then there’s the kind of popularity that appears in adolescence: status born of power and even dishonorable behavior.

Enviable as the cool kids may have seemed, Dr. Prinstein’s studies show unpleasant consequences. Those who were highest in status in high school, as well as those least liked in elementary school, are “most likely to engage(从事) in dangerous and risky behavior.”

In one study, Dr. Prinstein examined the two types of popularity in 235 adolescents, scoring the least liked, the most liked and the highest in status based on student surveys(调查研究). “We found that the least well-liked teens had become more aggressive over time toward their classmates. But so had those who were high in status. It clearly showed that while likability can lead to healthy adjustment, high status                                        has just the opposite effect on us.”

Dr. Prinstein has also found that the qualities that made the neighbors want you on a play date—sharing, kindness, openness—carry over to later years and make you better able to relate and connect with others.

In analyzing his and other research, Dr. Prinstein came to another conclusion: Not only is likability related to positive life outcomes, but it is also responsible for those outcomes, too. “Being liked creates opportunities for learning and for new kinds of life experiences that help somebody gain an advantage, ” he said.

6 . If maths is the language of the universe, bees may have just uttered their first words. New research suggests these busybodies of the insect world are capable of addition and subtraction (减法) — using colors in the place of plus and minus symbols.

In the animal kingdom, the ability to count — or at least distinguish between differing quantities — isn’t unusual: It has been seen in frogs, spiders, and even fish. But solving equations (方程式) using symbols is rare, so far only achieved by famously brainy animals such as chimpanzees and African grey parrots.

Building on previous research that says the social insects can count to four and understand the concept of zero, researchers wanted to test the limits of what their tiny brains can do.

Scientists trained 14 bees to link the colors blue and yellow to addition and subtraction, respectively. They placed the bees at the entrance of a Y-shaped maze (迷宫), where they were shown several shapes in either yellow or blue. If the shapes were blue, bees got a reward if they went to the end of the maze with one more blue shape (the other end had one less blue shape); if the shapes were yellow, they got a reward if they went to the end of the maze with one less yellow shape.

The testing worked the same way: Bees that “subtracted” one shape when they saw yellow, or “added” one shape when they saw blue were considered to have aced the test. The bees got the right answer 63% to 72% of the time, depending on the type of equation and the direction of the right answer — much better than random guesses would allow—the researchers report today in Science Advances.

Though the results came from just 14 bees, researchers say the advance is exciting. If a brain about 20,000 times smaller than ours can perform maths using symbols, it could pave the way to novel approaches in artificial intelligence (AI) and machine learning. Just don’t ask the bees to do your homework anytime soon.