问题
填空题
金属导体中定向移动形成电流的是______；在酸、碱、盐的水溶液里定向移动形成电流的是______．
答案
金属导体是依靠自由电子的定向移动形成电流的；酸、碱、盐溶液导电是依靠溶液中正负离子的定向移动形成电流的．
故答案为 自由电子；正、负离子．
搜题请搜索小程序“爱下问搜题”
金属导体中定向移动形成电流的是______；在酸、碱、盐的水溶液里定向移动形成电流的是______．
金属导体是依靠自由电子的定向移动形成电流的；酸、碱、盐溶液导电是依靠溶液中正负离子的定向移动形成电流的．
故答案为 自由电子；正、负离子．
| 阅读理解。 | ||
Research shows that humans switch from selfish to unselfish behaviour when they are watched. Do you?
somehow coded into humans and people respond this way unconsciously, or without realizing it. It is not just humans that act unselfishly when they are being watched. A fish called the grooming fish cleans other fish. When other fish are around, it is gentler. When no other fish are around, however, the grooming fish bites chunks from the fish it is supposed to be cleaning. The researchers suggest that the best way to get people to behave in the correct way is to make them feel watched. This could be the reason for the success of a famous American army poster. On it was a picture of an elderly man staring fiercely and pointing, it appeared, to the person who was looking at the poster. Under the picture was the caption "I Want You". It encouraged hundreds of thousands of young American men to join the army during the Second World War to fight the Germans and Japanese. | ||
| 1. According to the report, why does a person behave better when he feels he is being watched? | ||
[ ] | ||
| A. He does not want to be shamed by others. B. He needs to show he is a good person. C. He desires others to like him more. D. He feels he will receive some social reward. | ||
| 2. What is the text mainly about? | ||
[ ] | ||
A. It describes changed behaviour when observed. | ||
| 3. Where would the study described in the text most likely be found? | ||
[ ] | ||
| A. In a newspaper. B. In a scientific journal. C. In an advertising magazine. D. In a science textbook. |
