【简答题】电子邮件主要涉及3种网络协议,分别是____ 、____ 和____ 。
【单选题】已知集合 , ,若 ,则 的值等于( )
【单选题】已知集合 , ,若 ,则 的值等于( )
【单选题】阀型避雷器是由火花间隙和阀片电阻()组成。
【单选题】]The disinfection of various compartments in a vessel by filling them with a gaseous agent to destroy rats etc.means______.
【单选题】阀型避雷器主要由火花间隙和()串联组成。
【单选题】The disinfection of various compartments in a vessel by filling with a gaseous agent to destroy rats and all insects pests which act as germ carriers means().
【简答题】已知集合 , 若 , ,则 的值等于____.
【简答题】已知集合 ,若 , ,则 的值等于____.