机床坐标系的原点称为（）。 ["工件零点","编程零点","机械原点","空间零点"]
患者，男性，22岁，自发性气胸，行胸腔闭式引流术后，护士评估和观察要点是：（） ["评估患者生命体征及病情变化","观察引流液颜色、性质、量","观察长管内水柱波动，正常为3~4CM，咳嗽时有无气泡溢出","观察伤口敷料有无渗出液","观察患者有无皮下气肿"]
协方差为正值时，两种证券的收益变动趋同（）。
我国在唐代贞观年间发明了（） ["雕版印刷技术","泥活字印刷技术","木活字印刷技术","铜活字印刷技术"]
Cisco collaboration applications and services can be hosted in A number of ways, which three are valid hosting models?（） ["device-specific","on-premises","integrated","hybrid","virtual","SaaS"]
客运架空索道定义。
