介词短语 in the world 和定语从句 who are smarter than her都是修饰宾语从句中的主语 many people 的.由于, 介词短语较短, 为了保持句子平衡,最好把介词短语置于定语从句和先行词之间.这类不紧靠先行词的定语从句语法上叫【分隔定语从句】

再如：
This is the only book on the shelf that you can borrow.
He is the only student in my class who has failed in the exam.

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