Three years ago I failed an important exam in my life and became a student in a ordinary school. Disappointing as I felt at the shabby campus and the poorly-equipped classroom, I found the teachers patiently and considerate. Besides, I enjoyed the friendly atmosphere in class. I decided make the best of it. I worked hard and get along well with my teachers and classmates. Whenever I had difficulties, they were always available. Soon, I became one of the top student in my class, and which greatly increased my confidence and got him motivated.

My experience tell me that it is not what you are given but how you make use for it that determines who you are.

单域MPLS BGP VPN中，当PE和CE之间运行OSPF路由协议发现VPN用户路由时，为什么需要OSPF超级骨干区域（）。

A.为了保证VPN用户OSPF内部路由传递给同一VPN的其他Site时，仍然作为OSPF内部路由，而不会成为OSPF外部路由

B.为了使得用户OSPF协议报文比骨干OSPF路由更新报文具有更高的优先级

C.为了保证MPLS骨干区域的OSPF内部路由不被作为OSPF外部路由注入用户VPN内

D.为了保证VPN用户OSPF内部路由不会作为OSPF外部路由注入到骨干区域