It is ___ the customers' needs that has made chain stores so popular in big cities in China. [ ]

A. meeting          

B. met            

C. to have met      

D. being met

Pentium微处理器为了支持多用户、多任务操作，提供了4个特权级。操作系统核心程序和用户程序的特权级分别是______。

A．0级和1级

B．1级和2级

C．2级和3级

D．0级和3级