In order to reduce the increasing prices of vegetables , the toll(过路费)           if a truck carrying them passes through a toll station .

A．cancels

B．is cancelled

C．was cancelled

D．had been cancelled

下列关于催化剂装填说法正确的有（）。

A、催化剂装填可分为稀相装填和密相装填

B、密相装填能提高催化剂装填密度

C、密相装填的初始压力降较其他装填低

D、密相装填可以在不增加反应器投资的情况下提高加工能力