It is usually known that the Haiku poem ______ seventeen syllables.   [ ]

A. makes up  

B. consists of

C. is consisted of  

D. is made up

关于PIM-SM转发树描述错误的是（）

A.PIM-SM同时包含两种树：共享树和源路径树

B.从RP到组播接收者数据转发的路径成为共享树

C.从组播源到RP的数据转发路径成为源路径树

D.在共享树下，RPF检查使用组播原地址作为检测地址