《房地产开发企业资质管理规定》将房地产开发企业划分为4个资质等级，其中达到二级资质等级的条件为从事房地产经营（）年以上。 ["5","4","3","2"]
泌尿、男性生殖系统结核的原发病灶主要是（） ["肺","肠道","腹膜","骨关节","淋巴结"]
肺炎球菌肺炎（） ["粉红色乳状脓性痰","棕红色胶冻状痰","巧克力色腥味痰","脓性恶臭痰","铁锈色痰"]
急性绞窄性肠梗阻（） ["呕吐物无胆汁","呕吐物有多量胆汁","呕吐物为粪臭样","呕吐物为血性","呕吐物呈溢出性"]
下列疾病病理改变主要在肾，临床表现在膀胱的是（） ["肾结石","肾结核","多囊肾","肾肿瘤","肾脓肿"]
简述系统维护的过程。
