心肺复苏时,心外按压与人工通气的比,单人操作时是() ["15:2","20:2","30:2","15:1","30:1"]
通常可将土地划分为以下三类地价区段()。 ["商业路线价区段","农业种植区段","住宅片区段","工业片区段","农林片区段"]
照射剂量大于6Gy的外照射,引起的骨髓急性放射病为()。 ["极轻度","轻度","中度","重度","极重度"]
急性放射病主要病理变化有()。 ["造血功能障碍","出血或感染","生殖损害","A+B","A+B+C"]
以下几项病因能引起周围性呼吸衰竭的是() ["脑肿瘤","支气管肺炎","败血症中毒性脑病","一氧化碳中毒","化脓性脑膜炎"]
什么叫气象条件组合?线路正常运行情况下气象条件如如何组合?