阅读理解。 There's no doubt that fast food has become an important part of modern life, especially among teenagers. According to research, in the UK 80% of meals are eaten outside the home. And more than 50% of teenagers eat, on average, more than one hamburger every three days. The percentage is high and nutritionists (营养专 家) are worried, but is fast food really as harmful as they say it is? Here is what two experts, Jake Hyde and Ursula Birkbeck, have to say on the subject. ' Fast food is junk food,' says Jake Hyde. 'Fast food is of very little nutritional value. It is full of fat, especially the harmful type, which is found in meat, butter, cheese and mayonnaise . We need to cut down on fat if we want to stay healthy. Another thing is that fast food contains too much salt and sugar and too many additives (添加剂 ). It is also low in vitamins and fiber, because it includes hardly any vegetables. As a result, it doesn't provide us with enough nutrients, just lots of calories. Most teenagers who have made fast food an important part of their diet are overweight. This, along with the fact that they hardly ever take any exercise, puts their health at risk. It can lead to serious health problems like heart disease or diabetes.' 'People shouldn't feel guilty every time they have a burger,' says Ursula Birkbeck.' What is in it not that bad. Don't forget that red meat is a good source of iron and cheeseburgers (干酪汉堡包 ), for instance, contain calcium. Chips, which most people think are unhealthy, are not so bad after all, because potatoes are rich in Vitamin C. However, we shouldn't eat too much sauce or mayonnaise. Nowadays, fast food restaurants pay attention to health matters and nutrition. They have improved the quality of their food, use fewer additives, vegetable oil for cooking and some even use low-fat products. Also, most places offer salad bars, which give people the chance to balance fast food with vegetables that contain other nutrients. So, people don't need to prevent fast food from their diet completely. It's all a matter of what type of fast food they choose to eat, how often and what else they eat during the day.' 1. From the first paragraph we know that _____. A. it's doubtful that fast food has become an important part of modern life B. most meals in the UK are eaten inside the home C. over half of the British teenagers average over one hamburger every three days D. nutritionists are sure that fast food is very harmful 2. The underlined word 'mayonnaise' in Paragraph 3 is a type of ______. A. fat B. food C. meat D. additive 3. The difference of the two experts' opinions lies in ______ . A. whether fast food has little nutritional value B. whether fast food is full of fat C. whether fast food has improved its quality D. whether fast food restaurants pay attention to health matters 4. What would be the best title for the passage? A. Fast food-junk food B. Fast food-friend or enemy? C. Which expert is right? D. The fast food restaurants are improving