The speaker indicates that the dramatic critic is ______.

A．inclined to be objective

B．conditioned by certain requirements of his column

C．happy to oblige the backers of plays

D．suspicious of criticism directed against him

液相色谱法分析废水中阿特拉津，制备硅酸硅酸镁净化柱时，只需将硅酸镁吸附剂填入净化柱，轻轻敲打即可。