The boy with his parents            the Greener China since two years ago. [ ]

A. has joined

B. have been in

C. has been in

在linux系统中，查看系统中是否安装了dhcp的rpm包，应使用（）命令。

A、rpm -qa|grep dhcp

B、rpm -qf|grep dhcp

C、rpm -qi|grep dhcp

D、rpm -ql|grep dhc