For anyone who doubts that America is the land of the free, the ability of the Supreme Court to turn a question posed by a Pepsi distributor into a ruling that restricts presidential power ought to be reassuring.
词汇突破：Reassure安慰，使放心，使消除疑虑
主干识别：the ability ought to be reassuring.（这个句子的关键就是找出主干）
其他成分：For anyone who doubts that America is the land of the free，状语
of the Supreme Court to turn a question posed by a Pepsi distributor into a ruling that restricts presidential power (ability的定语)
