一个阅读jj里的长难句求分析～

啊GRE好难

Passage 197

❶Attempts to identify New Guinean’s hunter-gatherers face the well-known difficulty of defining what constitutes a hunter-gather group. ❷According to the common definition, hunter-gathers are those who subsist by hunting wild animals and gathering wild plants. ❸Yet those criteria beg numerous questions, including the issue of what constitutes “wild”. ❹The very presence on a landscape of humans who are consumers affects food resources, blurring the lines between wild and domesticated and, hence between hunting and pastoralism, and between gathering and cultivation. ❺Moreover, it is unclear how groups should be classified that are hunter-gatherers in their procurement strategies (获取资源的手段) but that make use of pastoralism and cultivation in their consumption patterns–– subsisting, for example, by trading wild foods to neighbors in return for domesticated crops.

最后一句话，我觉得这个语序更容易理解这句话，但是第一次读文章的时候没有直接反应过来。

it is unclear how groups【 that are hunter-gatherers in their procurement strategies (获取资源的手段) 】【but that make use of pastoralism and cultivation in their consumption patterns–– subsisting, for example, by trading wild foods to neighbors in return for domesticated crops. 】【should be classified】

想问大家，“should be classified” 提到that前应该怎么理解呀～第一次读的时候有点懵qwq