【单选题】—Jack, did you see my son Harry just now? —No,Mrs. White. I _______computer games.
【单选题】电梯能上下运行,能自动开关门;但按二层下召按钮不能登记。可是( )
【简答题】对电梯及电梯井的以下设计要求中,哪个是错误的?( )
【判断题】使用CD4017仿真流水灯时,每个发光二极管亮的时间相等。
【简答题】.----I can’t find Jack. Where did you see him this morning? ----It was in his factory _______he worked. A.where B.which C.that D.on which
【判断题】电梯按设备类别可分为乘客电梯、载货电梯、杂物电梯、自动扶梯和自动人行道。()
【单选题】—Did you see Jack at the wedding party? —No, he ______ by the time I ______ there.
【单选题】消防报警装置控制程序应符合的要求二层或二层以上楼层发生火灾,宜先接通( )