分析个句子：The reasons people abuse drugs are as different as people are from one another. 为什么

The reasons （that）people abuse drugs are as different as people are from one another

首先省略了关系代词that（当然也可以用why），句子主干是 the reasons are different ；定语从句修饰reasons，状语从句as...as修饰different，即以怎样的方式而不同。

翻译就是：人们滥用药物的原因各不相同，正如世界上没有相同的树叶（这里我套用了意译）。