题目

It’s time for class now. Please stop ________, boys and girls.         A. talking and playing        B. to talk and play           C. talk and play                D. talked and played 答案：A11．下列叙述正确的是（　　）A．1 L 0.2 mol•L-1 CH3COONa溶液中含有0.2NA个CH3COO-B．标准状况下，22.4 L CO2含有NA个碳氧双键C．一定温度下，将2 mol SO2和1 mol O2充入装有催化剂的容器中发生反应，转移4NA个电子D．1 mol羟基（-OH）中含9NA个电子