[怎么改标题才会有好心人来帮我??]GWD26-Q20与prep-2-08中过去完成时态的选择

3天了...这篇重发的帖子依旧没有多少回复...希望有人来解答..感谢! 

GWD26-Q20

In 1981 children in the United States spent an average
   of slightly less than two and a half hours a week doing
   household chores; by 1997 they had spent nearly six hours a week.
     

A.      chores; by 1997 they had spent nearly six hours
   a week

B.       chores; by 1997 that figure had grown to nearly
   six hours a week

C.      chores, whereas nearly six hours a week were
   spent in 1997

D.      chores, compared with a figure of nearly six hours a week in 1997

E.       chores, that figure growing to nearly six hours a week in 1997

这一题选B,当时大家的讨论结果是,分号隔开的两个句子时态无逻辑关系.

但是

下面PREP的这题选D明显的表明分号前后句子间时态有关系啊..请教能想通的同志们.谢谢谢谢请大家都来讨论~

8.    (24773-!-item-!-188;#058&001691)

Ozone, a special form of oxygen that screens out harmful ultraviolet rays, reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

(A) has long appeared that it was immune from

(B) has long appeared to have been immune from

(C) has long appeared as being immune to

(D) had long appeared immune to

(E) had long appeared that it was immune to