acitvity rating of catalyst的用法和样例：
- In the absence of catalyst, but the reduction rate of copper is low,and the effect of C/Cu2S ratio is obvious and that of CaO/Cu2S ratio is very small.
- The axial profile of pressure and circulating rate of catalyst in the standpipe and the influence of auxiliary air on them were measured.
- What's the going rate of computer programmers?
- By power we mean the rate of doing work.