People living in big modem cities are scarcely aware of the fact that there are still many people who are living in poor and filthy environments.

A. poverty-stricken


B. sloppy
C. sordid



D. solid

家电企业进行产品回收的物流系统属于（）

A.逆向系统

B.对称系统

C.偏进系统

D.偏出系统