题目

 P(g)十Q(g)R(s)，对此反应来说，下列能影响其反应速率的因素是：①温度②压强③生成物的浓度    (    )A、只有①    B．①和②    C、①和③    D、②和③  答案： BIt does no good ________ anything at such a time. [　　] A．sayingB．to say C．being saidD．to be said