【简答题】一台三相电力变压器,一、二次绕组分别为三角形联结和星形联结,额定容量S N =600kV·A,额定电压U 1N /U 2N =10000V/400V,问其电压、电流和阻抗基值各是多少?当一次电流(指线电流)为30A时,其标幺值为多大?
【单选题】— When is your first class? —It’s at 8:20 am. [ ]
【单选题】—________ today? —It's September third. [ ]
【单选题】---- ______does the meeting begin? ---- ______8:30. [ ]
【单选题】—_____? —It's eight-thirty. [ ]
【单选题】在对培养基进行间歇灭菌时,每次灭菌后要把培养一段时间,目的是