阅读理解。 Eat less and exercise more-it has long been a magic word for reducing those extra weight. But now it seems that all the hard work may have been in vain. Scientists say there are ten other reasons why people just keep getting bigger. They say that sleeping habits, central heating, medicines and even some pollutants (污染物) can play a role in weight gain. Traditionally, people have focused on diet and exercise to solve the problem. However the scientists from top US and Canadian universities say that other things must be considered. Lack of sleep could be partly the reason. In recent years, the average night's sleep has dropped from nine hours to just seven. Sleep shortage changes levels of the hormones (荷尔蒙) that control food intake and body fat and increase hunger and appetite. If it is too hot or too cold, we burn calories (卡路里) to cool down or heat up. But if the temperature is just right, the calories may be turned into body fat instead. Those who take medicine to control their blood pressure can often put on weight. Similarly, studies have shown that going on the Pill can add to a woman's weight. Mother nature may also be the reason, with our body shape being partly inherited (遗传的). The overweight are also more likely to settle with partners of a similar size. And their children are more likely to be obese (肥胖的). And the use of pollutants is on the rise, say the researchers. The man-made chemicals in pesticides (杀虫剂) and plastics can lead to weight gain. Your mother's age and your weight at birth are also important, with older woman more likely to have obese children and underweight babies having a bigger chance of being obese in later life. We also tend to put on weight as we get older. Finally, giving up smoking can also help pile on the pounds. The scientists from Yale, Cornell and Johns Hopkins said there was some evidence supporting poor diet and lack of exercise as the main causes of obesity. 1. Which is commonly thought to be effective in losing weight? A. To have operation to cut extra fat. B. To take pills and avoid fatty food. C. To sleep less to burn more calories. D. To have less food and take more exercise. 2. Which of the following factors doesn't lead to overweight? A. Regular and enough sleep. B. Comfortable living environment. C. Not enough physical exercise. D. harmful chemicals in the food. 3. Which of the following statements would the author agree to? A. Lack of sleep leads you to take in more food. B. Unpleasant weather helps you to put on weight. C. Obese parents are not likely to have fat children. D. Medicine for blood pressure helps you lose weight. 4. What would women prefer to do to have healthy children? A. To have only one child. B. To marry at an older age. C. To marry a strong husband. D. To give birth to a baby at younger age.