题目

—How many computers are there in the room? —__________. Some workers moved them to another place just now. A. None  B. Both    C. Nobody      D. Neither 答案：A将下列离子方程式改写成化学方程式：（1）CO32—+2H+=CO2↑+H2O： （2）Cu2++2OH—=Cu(OH)2↓： （3）Zn+2Ag+=Zn2++2Ag ：