Langue refers to the a（）linguistic system shared by all the members of a speech community while the parole is the concrete use of the conventions and application of the rules.
把乙炔钢瓶放在操作时有电弧火花发生的实验室里。
可锻铸铁是在钢的基体上分布着（）石墨。 粗片状。 细片状。 团絮状。 球粒状。
中国城市管理体制有何特点？
Questions 26 to 30 are based on the following passage.
Exercise is one of the few factors with a positive role in long-term maintenance of body weight. Unfortunately, that message has not gotten through to the average American, who would rather try switching to “light” beer and low-calorie bread than increase physical exertion. The Centers for Disease Control, for example, found that fewer than one-fourth of overweight adults who were trying to shed pounds said they were combining exercise with their diet.
In rejecting exercise, some people may be discouraged too much by caloric-expenditure charts: for example, one would have to briskly walk three miles just to work off the 275 calories in one delicious Danish pastry (小甜饼). Even exercise professionals concede half a point here. “Exercise by itself is a very tough way to lose weight,” says York Onnen, program director of the President’s Council on Physical Fitness and Sports.
Still, exercise’s supporting role in weight reduction is vital. A study at the Boston University Medical Center of overweight police officers and other public employees confirmed that those who dieted without exercise regained almost all their old weight, while those who worked exercise into their daily routine maintained their new weight.
If you have been sedentary (极少活动的) and decide to start walking one mile a day, the added exercise could burn an extra 100 calories daily. In a year’s time, assuming no increase in food intake, you could lose ten pounds. By increasing the distance of your walks gradually and making other dietary adjustments, you may lose even more weight.
What is the author’s purpose in writing this article? （） To justify the study of the Boston University Medical Center.。 To stress the importance of maintaining proper weight.。 To support the statement made by York Onnen.。 To show the most effective way to lose weight.。
消费者协会的职能包括（）
