填空题. A. severe B. generally C. treatment D. mistaken E. challenges F. disapprove G. matter H. rigorous I. magic J. suspected K. publically L. factors M. faulty N. based O. questioned Scientists have finally figured out how the key gene tied to obesity makes people fat, a major discovery that could open the door to an entirely new approach to the problem beyond diet and exercise. Since 2007, researchers have known that a gene called FTO was related to obesity, but they didn't know how, and could not tie it to appetite or other known 11 . Now experiments reveal that a 12 version of the gene causes energy from food to be stored as fat. Genetic tinkering in mice and on human cells in the lab suggests this can be reversed, giving hope that a drug or other 13 might be developed to do the same in people. The discovery 14 the notion that "when people get obese it was basically their own choice because they choose to eat too much or not exercise," said study leader Melina Claussnitzer, a genetics specialist. For the first time, genetics has revealed a mechanism in obesity that was not really 15 before and gives a third explanation or factor that's involved. Several obesity drugs are already on the market, but they are 16 used for short-term weight loss and are aimed at the brain and appetite; they don't directly target metabolism. Researchers can't guess how long it might take before a drug 17 on the new findings becomes available. But it's unlikely it would be a 18 pill that would enable people to eat anything they want without packing on the pounds. And targeting this fat pathway could affect other things, so a treatment would need 19 testing to prove safe and effective. The gene glitch doesn't explain all obesity. It was found in 44 percent of Europeans but only 5 percent of blacks, so other genes clearly are at work, and food and exercise still 20 .