第4题: [单项选择]What do we learn about deserts from this text A. Deserts can change into green and fertile areas. B. Certain areas have always been desert. C. Deserts were once the home of elephants and giraffes. D. Deserts have been growing since the beginning of the worl 参考答案:A 答案解析:文章第二段第六行“Throughout history deserts have been expanding and retreating again.”这段中谈到,一些肥沃的地方以前曾经是沙漠,而
第25题: [单项选择]治疗成人呼吸窘迫综合征最有效的措施为()。 A. 低浓度持续吸氧 B. 高浓度吸氧 C. 正压机械通气 D. 呼气末正压通气 E. 应用糖皮质激素 参考答案:D 答案解析:一旦诊断为呼吸窘迫综合征(ARDS),应尽早进行机械通气。机械通气的目的是提供充分的通气和氧合,以支持器官功能。通气的关键在于:复张萎陷的肺泡并使其维持在开放状态,以增加肺容积和改善氧合,同时避免肺泡