【单选题】已知苯酚的 K a =1.05×10 -10 ,则浓度为 1.0×10 -3 mol·L -1 苯酚钠溶液的 pH 为 :
【单选题】有多种设备可以实现不同网段或网络之间的互联,互联设备通常可按工作在OSI模型中的层次来划分。在物理层实现互联的称为(53);在数据链路层实现互联的称为(54);在网络层实现互联的称为(55);在运输层及以上高层实现互联的设备称为网关或(56)。(57)也是一种用来构造局域网的常用设备,通常可以用双绞线把服务器与PC客户机等连入(58)。
【判断题】Many businesses need systems that will integrate information for the various organizational levels and functions.
【简答题】_______ EarthWatch works with many companies to promote good practice._______ Businesses need to change the way they operate in order to help and reduce their effect on the environment. _______ ...