In a country that reveres its runners,many of whom are the b

In a country that reveres its runners,many of whom are the best in the world,it is no surprise..
句子成分分析。

句子中心结构是it（主） is（系） no surprise（表）.主系表结构.
然后in a country that revers its runners这个短语在句中作状语,交待事情的地点.
最后many of whom are the best in the world是作前面runners的定语,构成定语从句,作用是修饰runners是怎样的runners.