OG17 Verbal SC 301 Inuits of the Bering Sea

tobiasbj

Inuits of the Bering Sea were in isolation from contact with Europeans longer than Aleuts or Inuits of the North Pacific and northern Alaska.
(A) in isolation from contact with Europeans longer than
(B) isolated from contact with Europeans longer than
(C) in isolation from contact with Europeans longer than were
(D) isolated from contact with Europeans longer than were
(E) in isolation and without contacts with Europeans longer than

正确答案为D，目前我理解B和D的差异在于B产生了ambiguity，有两种解释方法
1. Inuits were isolated from contact with Europeans longer than from contact with Aluets and Inuits
2. Inuits were isolated from contact with Europeans longer than Aluets were isolated from contact from Europeans

Inuits of the Bering Sea were isolated from contact with Europeans longer than were Aleuts or Inuits of the North Pacific and northern Alaska.
完整的句子应该是怎样的？看到than were Aleuts感觉很奇怪，希望能有人：
1 帮忙填满句子
2 解释一下 什么情况下容易出现比较级中的ambiguity 以及怎样避免
谢谢！