[解析]
(1)推理判断题。根据第二段In fact,this is part of the school's health class.It includes heart health,nutrition(营养) and fitness.Students can learn basic knowledge about fats,proteins(蛋白质),calories and sugar.(事实上,这是学校健康课的一部分。它包括心脏健康、营养和健身。学生可以学习有关脂肪、蛋白质、卡路里和糖的基本知识。)和第三段第一句 Students learn how to balance calories in and out.(学生们学习如何平衡卡路里的摄入和消耗)可知,在上了健康课之后,学生们尽力保持均衡的饮食。故选A。
(2)细节理解题。根据第二段In fact,this is part of the school's health class.It includes heart health,nutrition(营养) and fitness.Students can learn basic knowledge about fats,proteins(蛋白质),calories and sugar.(事实上,这是学校健康课的一部分。它包括心脏健康、营养和健身。学生可以学习有关脂肪、蛋白质、卡路里和糖的基本知识。)可知,通过前两段我们了解到学生在上课时学习有关健康和营养的知识。故选B。
(3)细节理解题。根据第三段The online calorie counter has turned out to be a cool tool to help you make healthy choices.Making one healthy eating decision can really make a difference."(在线卡路里计数器已经成为一个很酷的工具,可以帮助你做出健康的选择。做出一个健康的饮食决定真的能带来不同。)可知,Adam Carlson认为健康的饮食习惯很重要。故选D。
(4)标题归纳题。根据第一段How many calories are there in every meal you eat?That seems like a difficult question to answer.But students at Aitkin High School in the United States can easily answer it now.They put what they eat into an online calorie counter(计算器).It quickly measures the amount of calories in their meals.(你每顿饭有多少卡路里?这似乎是个很难回答的问题。但是美国艾特金高中的学生现在可以轻松地回答这个问题。他们把自己吃的东西输入一个在线卡路里计数器,它会迅速计算出他们每顿饭中的卡路里量。)可知本文讲述的是人们应该计算每天吃的食物里的卡路里,以保持健康。所以"B.Counting calories to stay healthy计算卡路里以保持健康"为最佳标题。故选B。