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划分句子成分有助于理解句子意思和修饰关系：
①【Research 主语】【is谓语】【 also the chief （means 定语从句先行词）表语】【 by which we humans attempt to satisfy our instatiable appetite for knowledge,and our craving to understand ourselves and the world around us.定语从句】
②by which 【we从句主语 】【humans 同位语】【attempt to satisfy 谓语】【（our instatiable appetite for knowledge）,and （our craving ）并列宾语】
【to understand ourselves and the world around us不定式短语,做 定语,修饰第二个宾语】就是说means 是先行词吗， 那为什么要用by which呢，看不出后面的部分有比较的意思 用in which不行吗介词加关系词的使用，涉及一个固定短语：【用这种方式/方法】：by this meansmeans做先行词，介词+关系词就只能是by which还有一个表达：in this way即 way 做先行词，表示【用这种方式/方法】，介词+关系词那就是 in which.