【简答题】下列各物质的分子间只存在色散力的是( )A. B. C. D. HBr E. F. G.
【单选题】加工时需刮去粗皮,堆置“发汗”至内皮呈暗紫色的皮类中药是
【单选题】在某一化学反应中,反应物A的浓度在20s内从1.0mol/L变为0.2mol/L,则在这20s内以A浓度的变化表示的平均反应速率为( )
【简答题】__________ is often more difficult to find trained men than to get financial support for scientific research. A. It B. That C. This D. What
【单选题】My brother while he his bike and hurt himself.
A.
had fellen; was riding