题目

John, together with some American soldiers who       sent to Iraq,        killed in a bomb explosion.   A．were; were              B．was; was             C．were; was           D．was; were 答案：C 某温度下，向体积固定的密闭容器中充入2 mol NO2气体，达平衡后，混合气体的压强为p．维持温度不变，向该容器中继续充入a mol N2O4气体．再达平衡时，容器内气体总压强恰好为原平衡的2倍，则 [　　] A． a＜1 B． a＝1 C． 1＜a＜2 D． a＝2