简要说明催化剂密相输送原理。
参考答案：
密相输送常以少量气体输送大量固体，输送推动力为静压差，用以克服沿程摩擦力。
I just expressed my thoughts on it and what I said only applies ______ some of you.
A．to
B．for
C．with
D．on
