A. 从下列单词中选择适当的词填空，每个词只能用一次。

which         that            was         guidelines to             response     things         two baked         available     close         children

Public schools raise cash by selling their students everything from biscuits to soft drinks. This contributes  51 America's childhood overweight problem. The proportion of overweight  52 in the United States more than doubled between 1980 and 2004. For adolescents, that number has more than tripled.

In  53 , Congress commissioned a study to examine the snacks sold outside the federally regulated school lunch program. The aim  54 to produce sensible recommendations on what schools should—and should not—offer. The Institute of Medicine responded with  55 sure to upset the average soda-drinking high-schooler.

The institute's experts created  56 tiers of snack foods that schools might sell instead of junk. The first contains  57 such as fruits, vegetables, non-fat yogurt and whole-grain chips. These should be  58 to all students any time during the school day. Less nutritious—but not unhealthful—snacks such as  59 potato chips and diet soft drinks are in the second category,  60 high school students only ought to be able to purchase after school. Sure, students can always bring junk food from home.

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