请教新版prep上一题sc

明天就考了，大家请帮个忙，谢谢！

第一题是prep里面的，我当时选A，因为印象里面我看到有种说法说当not only后面的谓语倒装是，可以用but it also的形式。但是原题或者讨论我没找到（至少在大全里没看到）Ａ可能的错误也许就是出在gave上面（做题的时候我没发现），但是D这种为什么对呢？

Not only did the systematic clearing of forests in the United States create farmland (especially in the Northeast) and gave consumers relatively inexpensive houses and furniture, but it also caused erosion and very quickly deforested whole regions.
A. Not only did the systematic clearing of forests in the United States create farmland (especially in the Northeast) and gave consumers relatively inexpensive houses and furniture, but it also
B. Not only did the systematic clearing of forests in the United States create farmland (especially in the Northeast), which gave consumers relatively inexpensive houses and furniture, but also
C. The systematic clearing of forests in the United States, creating farmland (especially in the Northeast) and giving consumers relatively inexpensive houses and furniture, but also
D. The systematic clearing of forests in the United States created farmland (especially in the Northeast) and gave consumers relatively inexpensive houses and furniture, but it also
  
E. The systematic clearing of forests in the United States not only created farmland (especially in the Northeast), giving consumers relatively inexpensive houses and furniture, but it

189. By offering lower prices and a menu of personal communications options, such as caller identification and voice mail, the new telecommunications company has not only captured customers from other phone companies but also forced them to offer competitive prices.
(A) has not only captured customers from other phone companies but also forced them
(B) has not only captured customers from other phone companies, but it also forced them
(C) has not only captured customers from other phone companies but also forced these companies
(D) not only has captured customers from other phone companies but also these companies have been forced
(E) not only captured customers from other phone companies, but it also has forced them

C, the best choice, correctly uses the parallel construction has not only x’d but also y’d and avoids ambiguity of reference by using these companies rather than them. In A, B, and E, the referent of the pronoun them is ambiguous; because them appears to be parallel to customers, the illogical suggestion is that the new telecommunications company has forced customers to offer competitive prices. Choices B and E may also be faulted for the improper insertion of it to refer redundantly to the new company. Finally, E is not parallel in verb tense with captured... has forced. Choice D does not maintain parallelism, unnecessarily shifting from active (company not only has captured) to passive (but also these companies have been forced).

og的解释也说了在主语一致的情况下插入代词是多余的。经过这两题的比较，能否说not only, but also如果同时出现在划线部分就不一定能作为判断点呢？

请赐教。。。

（看了下之前的讨论，好像有点启发）

本题里not only..but also没有but also好，因为是转折关系而不是递进关系 >_< 不过考试的时候哪里想得到这么多。。。

第一题前后是转折的关系.前半句是说the systematic clearing of forests带来的好处,后半句是说它带来的坏处.BUT在这里是转折连词,ALSO是副词,而不是像not only but also的固定搭配.
not only but also应用于递进关系的固定搭配,就是说"A不但...也...",前后部分都得说它好,或者都得说它坏.

后面一题是not only but also的应用,是说新的公司不但从其他公司挖到顾客,也让这些公司降价.递进关系.