单项选择题
A．snRNA B．mRNA C．tRNA D．hnRNA
A．清洁中段尿培养，菌落计数为500个/ml B．清洁中段尿培养，菌落计数为1000个/ml C．清洁中段尿培养，菌落计数为1万个/ml D．清洁中段尿培养，菌落计数为5万个/ml