题目

My sister, an inexperienced rider, was found sitting on the bicycle ______ to balance it. A. having tried        B. trying                      C. to try                             D. tried 答案：B仅改变下列一个条件，通过提高活化分子的百分率来提高反应速率的是     (      )A．加热           B．加压       C．减少生成物浓度                  D．加大反应物浓度