题目

20世纪初，科学家发现，某些物质在很低的温度时，电阻就变成了零，这就是_____现象。如果能制造出常温下的超导体，它可以在下列哪些情景中得到应用_____（选填字母）。A．用作输电线 B．制成白炽灯泡的灯丝 C．绕制成电动机的线圈 D．用作电吹风的电热丝。 答案：【答案】超导 AC 【解析】超导体的电阻为零，电流流过超导体时不会产生热量，凡是利用电流热效应工作的设备，都不能使用超导体．(1)当导体的温度降至某一低温时，它的电阻突然变为零，这种现象就是超导现象；(2)超导体电阻是零，所以超导体不会将电能转化成内能，不会放热。利用电流热效应工 Old habits, especially bad ones, can be hard to break.People often make fun of New Year's resolutions (决心). However, resolutions present a big opportunity for self-improvement. Fortunately, social science has some ideas about how to start a good habit and stick to it.Gary Charness and Uri Gneezy, two scientists at the University of Chicago, did some research, where 120 students were asked to take part in an experiment about exercise habits, and each of them would get $175 in the end. The students were randomly assigned (随机分配) to three groups. The first group got the money for just giving researchers permission (允许) to record their gym attendance. The second group gave permission, but had to go to the gym at least once the next month. The final group gave permission and had to go to the gym eight times that month.Unsurprisingly, the group that had to make eight gym visits to get paid exercised more than the other two groups. After the payments stopped, these students kept going to the gym at higher rates (频率). They went to the gym about twice as often as the other two groups.In another study, researchers invited 151 students to work out in the gym, and randomly assigned 75 to a “temptation-bundling” group. As they exercised, they listened to the start of an attractive audio-novel (有声小说). At the end of their workout, students were told that if they wanted to hear what happened next in their book, they would have to come back to the gym. They could only listen to the audio-book while exercising. The other 76 students also completed the first workout but without any kind of temptation bundle.It turned out that the students in the temptation-bundling group visited the gym 27% more often than the control group over the next seven weeks. Sadly, the temptation-bundling trick fell apart over the Thanksgiving holiday when the gym was closed. The studies show that trying something new quite often for as little as a month can kick-start a lasting change in behavior. Moreover, “temptation-bundling” may also be a useful method for changing behavior, particularly when used together with other methods. Even if you cannot promise yourself to stick with something for long, there is a huge benefit in putting in a lot of energy for a few weeks. It may pay off for longer than you think. So, why not challenge yourself with next New Year's resolution?1.What can we learn from the two studies?A.The students got different payments according to their gym attendance.B.The temptation-bundling group loved audio-novels more than the other group.C.27% of students in the temptation-bundling group exercised more often than before.D.The students who exercised more often at first were more likely to keep working out.2.The third paragraph is mainly about __________.A.how the research was performed B.what was found in the researchC.why the scientists did the research D.who took part in the research3.The underlined word “temptation-bundling” in Paragraph 5 probably means __________.A.forming new habits by trying something you didn't like beforeB.connecting something you like with something you have to doC.improving your workout skills by listening to audio-booksD.pushing yourself by doing two tasks at the same time4.What is the writer's main purpose in writing this passage?A.To encourage people to go to the gym more often.B.To present a new way to do scientific research.C.To offer advice on how to develop a good habit.D.To stress the importance of New Year's resolutions.