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试述上皮细胞侧面都有哪些细胞连接？（2分）
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Ants first captured the attention of software engineers in the early 1990s. A single ant cannot do much on its own, but a group of ants (51) can solve complex problems. That inspired people like Marco Dorigo, who is one of the founders of a (52) known as group intelligence. Ants are good at choosing the shortest possible route between a food (53) and their nest. This reminds us of a classic computational travelling-salesman problem. Given a list of cities and their (54) apart, the salesman must find the shortest route needed to visit each city once. As the number of cities (55) , the problem gets more complicated. Ants solve their own problem using chemical signals called pheromones (信息素), when an ant finds food, she takes it back to the nest, (56) a pheromone trail that will attract others. The more ants that (57) the trail, the stronger it becomes. (58) , the pheromones evaporate (挥发) quickly, so once all the food has been collected, the trail soon goes cold. This rapid evaporation means long trails are less (59) than short ones, all else being equal. Pheromones thus turn the (60) intelligence of the individual ants into something more powerful.
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Who says your job leaves you no time to hit the gym A detailed new study of U. S. physical activity patterns shows that men who work full-time—whether their jobs are active or sedentary— end up getting more exercise than healthy working-age men without a job. The new study comes from researchers at the National Institutes of Health (NIH). As part of the National Health and Nutrition Examination Survey in 2003, some 1,800 working-age adults were asked questions about their lifestyle and work habits, and, most importantly, they then agreed to wear an accelerometer—a device to measure their physical activity—over the course of several days. Those data from the accelerometers provide a rare opportunity to nail down how much activity the typical American actually does. They show that men or women who work in active jobs do more physical activity on weekdays than men or women working in sedentary jobs: that’s perhaps not surprising, but the NIH researchers suggest that it still matters because of an ongoing shift in the economy toward sedentary work. The more surprising finding is the one that compares full-time workers to people who don’t work. The study shows that men with full-time jobs do more physical activity than healthy men without jobs. ("Healthy men", in this case, were those men who said their primary reason for being out of work—was something other than health or disability.) In fact, even sedentary full- time workers performed more weekday physical activity overall than the healthy non-workers. The results looked very different for women. Women in sedentary jobs did less physical activity on weekdays than their healthy non-working peers. So what drives the gender (性别) difference The study looks at the pattems, and unfortunately can’t provide too much detail about their causes. There could be many possible answers, including, perhaps, different abilities to pay for leisure time activities or different attitudes about work and physical activity. It could also be that more non-working women than men are choosing to be at home running around full-time after the kids. But the NHK researchers do find evidence, they write, to suggest that, whatever causes the difference, healthy non-working women "are replacing work with active pursuits whereas" —for some reason— "non-working men generally are not. \ The study tries to identify ______.
论述题 联系实际谈谈如何保持中学生的心理健康。
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