[单项选择]The ozone layer plays as great a role in the stability of spaceship Earth as ______ the waters of its lakes, ponds, oceans, rivers, and streams. A. do B. does C. play D. are
第3题: [单项选择]亚急性细菌性心内膜炎的发生 A. 由致病力强的化脓菌引起 B. 由致病力弱的草绿色链球菌引起 C. 与A组溶血性链球菌感染有关 D. 与系统性红斑狼疮有关 E. 与慢性消耗性疾病有关 参考答案:B 答案解析:[解释] 风湿性心内膜炎的发生与A组溶血性链球菌感染密切相关,亚急性细菌性心内膜炎的发生由致病力弱的草绿色链球菌引起,急性细菌性心内膜炎由致病力强的化脓菌引起,而无菌性血栓性心内膜炎与慢性消耗性疾病有