反应器按（）分为固定床和流化床反应器。
A.用途
B.壁温度
C.介质流向
D.催化剂床层的状态
参考答案：D
---In recent years more and more Indians like traveling in Asia during May Day.
--- .
A．So do we Chinese
B．Neither do we Chinese
C．So we Chinese do
D．Neither we Chinese will
任何空间刚体未定位时都具有几个自由度？
