请教...助动词的补出问题

224. 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

    in isolation from

(B)   isolated

(D)    
were  

助动词在考试中尽量补出原则

答案；D

1) 补得对不对

2) 和没补的有没有什么其它区别

were可以倒装，没有关系，补出是为了消除歧义。