工业上固体催化剂是由（）组成的。
A、正催化剂和负催化剂
B、主催化剂和辅催化剂
C、活性组分、助催化剂和载体
D、活性组分、稳定剂和载体
参考答案：C
What the leader referred to in the report was really something _______. [ ]
A. worthy of considering
B. worth to be considered
C. worthy to be considered
D. worth being considered
列举五种有汇流母线的电气设备连接方式：单母线、单母线分段、双母线、（）、一台半断路器接线。
