2. 外语
  3. Excessive calories from sugar can contribute to weight problems, and sugar is also well known for its ability to promote teeth d

Excessive calories from sugar can contribute to weight problems, and sugar is also well known for its ability to promote teeth d

admin2012-10-19  46
问题     Excessive calories from sugar can contribute to weight problems, and
sugar is also well known for its ability to promote teeth decay. Too many (1)______
calories from fat have also taken their toll from the public’s health. In 1988, (2)______
the U.S. surgeon general issued a report linking high levels of fat intake to
an increased risk for obesity.
    Obesity is a risk factor for high bloody pressure, stroke, and diabetes. (3)______
Research has also shown a relationship between high levels of fat in the
diet and cancer. In addition, scientists have linked some types of fat to high
blood cholesterol levels, which must lead to heart disease. Such reports (4)______
have prompted health experts and nutritionists to recommend that adults and
children over age 2 not only watch their sugar intake but also to limit their (5)______
fat intake to a maximum of 30% of their complete calories. This has encour- (6)______
aged many people to turn to products made with fat and sugar substitutes.
Low-calorie sugar substitutes have been around for decades, but the recent
trend in eating "light" has created a boom in this branch of food-technology
research. Today, food chemists are seeking for better substitutes by modify- (7)______
ing existing foods, searching for new compounds in nature, and concoct (8)______
entirely new substances. But the research process is complicated by our
incomplete understanding of how the human body interacts with the chemicals we eat.
    For example, scientists do not already know exactly why some substanc- (9)______
es taste sweet. Other questions involve the safe and usefulness of artificial (10)______
fats and sweeteners.
(4)
选项
答案must — may/can
解析 must的推测性用法表示“一定是、一定会”，说话者对所作出的推测十分有把握，一般来说，上下文或语境应该有足够的线索，才可以恰当地使用must，否则可能会造成语义上的不恰当。这里，上下文并没有说这些类型的脂肪和心脏病有必然的联系，所以用must是不恰当的，应该用can或may合适。
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