A. To outline contrasting types of economic systems. B. To explain the science of economics. C. To argue for the superiority of one economic system. D. To compare barter and money-exchange markets. 参考答案:A 答案解析:本题为细节归纳题。据第1段导入段及后面各段的内容可确定。
第29题: [单项选择]患儿男,2岁,因“呕吐、腹泻1d”来诊。1d前突然脐周阵发性痛,后恶心,呕吐3~4次,排粪5~6次,初呈蛋花汤样,后呈赤豆汤血水样,伴腥臭。查体:T39℃;精神反应差;未见皮疹;腹软,稍胀,不固定压痛点,无腹肌紧张,未及包块。为早期确诊,最有价值的检查是() A. 腹部X线片 B. 粪细菌培养+药敏试验 C. 粪常规和隐血试验 D. 血白细胞计数和分类 E. 腹部超声 参考答案:A