关于Linux说法正确的是______。

A．Linux操作系统与Windows NT、NetWare、UNIX等传统网络操作系统最大的区别在于免费

B．Linux是单用户多任务的操作系统

C．Linux不是UNIX的变种，因此不能将Linux上的程序移植到UNIX主机上运行

D．Linux操作系统具有虚拟内存的能力，可以利用硬盘来扩展内存

This has been my life. I have found it worth living, and ____ it gladly again if I _____ the chance.

A．would live; had

B．had lived; have had

C．have lived; had

D．would live; had had