第30题: [单项选择]正常菌群在构成生态平衡中起重要作用,其生理学意义及特征中不包括( ) A. 生物拮抗 B. 营养作用 C. 促进宿主免疫器官的发育成熟 D. 持续刺激宿主免疫系统发生免疫应答 E. 成年后肠道中双歧杆菌占肠道的比例明显增加 参考答案:E 答案解析:[解析] 健康婴幼儿粪便中主要是双歧杆菌、拟杆菌、肠杆菌、肠球菌、葡萄球菌等;成人粪便中球菌和杆菌的比例约为1:10。
第31题: [单项选择]Mr Brown is making inquiries about A. full parking facilities. B. leaving his car in the U. K. C. having his car serviced. D. hiring a car abroa 参考答案:B 答案解析:[听力原文] 1-5 Clerk: Good morning, sir. Can I help you Customer: I want to make inquiries about l