What is the minimum number of balls这个是句子的主干
you must pick out to guarantee 3 balls of the same color是balls的定语
定语中to guarantee 3 balls of the same color是pick up balls的目的状语
整个句子翻译过来就是 如果要保证有3个相同颜色的球的话,你所应挑出的球的数量最小是多少?
【the minimum number of balls】是主句,【you must pick out to garantee 3 balls of the same colors】做定语从句,修饰balls
特殊疑问句 中间有定语从句
you must……到句末修饰前面的ball
为了保证有3个球具有同样的颜色,你最少挑选出几个球?