One of the most widely accepted, commonly repeated assumptions (假设) in our culture is that

One of the most widely accepted, monly repeated assumptions (假设) in our culture is that if you exercise, you will lose weight. I exercise all the time, but I still have gut fat that hangs over my belt when I sit. Why isn’t all the exercise getting rid of it?
It’s a question many of us could ask. More than 45 million Americans now belong to a health club, up from 23 million in 1993. We spend some $19 billion a year on gym memberships. Of course, some people join and never go. Still, as one major study — the Minnesota Heart Survey — found, more of us at least say we exercise regularly.
And yet obesity (肥胖) figures have risen sharply in the same period: a third of Americans are obese, and another third count as overweight by the Federal Government’s definition. Yes, it’s entirely possible that those of us who regularly go to the gym would weigh even more if we exercised less. But like many other people, I get hungry after I exercise, so I often eat more on the days I work out than on the days I don’t. Could exercise actually be keeping me from losing weight?
The popular belief that exercise is essential for weight control is actually fairly new. As recently as the 1960s, doctors routinely advised against too much exercise, particularly for older adults who could injure themselves. Today doctors encourage even their oldest patients to exercise, which is sound advice for many reasons: People who regularly exercise are at significantly lower risk for all manner of diseases — those of the heart in particular. They less often develop cancer and many other illnesses. But the past few years of obesity research show that the role of exercise in weight loss has been wildly over-evaluated.
“In general, for weight loss, exercise is pretty useless,” says Eric Ravussin, exercise researcher at Louisiana State University. Many recent studies have found that exercise isn’t as important in helping people lose weight as you hear so regularly in gym advertisements or on shows like The Biggest Loser — or, for that matter, from magazines like this one.
The basic problem is that while it’s true that exercise burns calories and that you must burn calories to lose weight, exercise has another effect: it can make one hungry. That causes us to eat more, which in turn can negate (使无效) the weight-loss benefits we just gained. Exercise, in other words, isn’t necessarily helping us lose weight. It may even be making it harder.
【小题1】 From the passage we learn that     .A．some Americans join a health club but never go thereB．the number of overweight people has doubled since 1993C．more than 45 million Americans now go to the gym regularly D．Americans waste too much money each year on sports【小题2】 According to the passage, exercise     .A．has long been believed to be good for older adults B．is not properly advertised as an effective way to lose weight C．was first recognized as an effective way to lose weight in the 1960sD．is less effective in preventing heart disease than what doctors believe【小题3】According to the writer, people might gain weight because     .A．they have the habit of going to the gym regularlyB．they eat the same food when they do not exerciseC．they exercise less than required by doctorsD．they eat more after they exercise【小题4】What may be the best title for this passage?A．Overweight Is Not Good for Your HealthB．Exercise Won’t Make You ThinC．Gym Is Part of American LifestyleD．Obesity Is a Social Problem in America A