GMATprep和OG上的一个巨大语法冲突

发现一个巨大的冲突，颠覆了我对比较结构所有题目的理解。后天就要考试了，请大牛们帮我。谢谢！

下面这题来自于gmatprep:

There is a widespread belief in the US and Western Europe that young people
have
                a smaller commitment to work and a career than their parents and
grandparents
            and that the source of the change lies in the collapse of the
'work ethic'.

A. a smaller commitment to work and a career than their parents and grandparents

B. less of a commitment to work and a career than their parents and grandparents

C. a smaller commitment to work and a career than their parents and grandparents

D. less of a commitment to work and a career than their parents and grandparents
had

E. a lessening of the commitment to work and a career than their parents and
grandparents had

答案是D。

这个思路与OG完全冲突。OG上面的所有比较结构的题目，都是如果比较结构后面的谓语和比较结构前面的谓语相同的话，则用did/do/does来代替比较结构后面的谓语，如果比较结构前面有情态动词，助动词，则比较结构后要保留相应的情态动词和助动词，省略情态动词和助动词后面的动词。OG上面所有题目都遵循这一规律。可是GMATprep上的这个题目居然用了"had"，也就是说应该在比较结构前面应该出现一个完成时的结构，可是却没有，按照OG的规律的话此处应该用did才正确。had的选项绝对应该是错误的。

up

OG 里面的动词指代有补出助动词 did 的。

如：168. Today, because of improvements in agricultural technology, the same amount of acreage produces double the apples that it has in 1910.
(A) double the apples that it has
(B) twice as many apples as it did
(C) as much as twice the apples it has
(D) two times as many apples as there were
(E) a doubling of the apples that it did
Choice B, the best answer, correctly uses the adverbial phrase twice as many... to modify the verb produces; properly employs many rather than much to describe a quantity made up of countable units (apples); and appropriately substitutes did for the understood produced to express the logically necessary past tense of produces. Choice A awkwardly substitutes the adjective double for twice; uses that without a clear referent; and misuses has to refer to events occurring in 1910. Choice C employs the incorrect much in a wordy construction and also misuses has. D is wordy and imprecise;... as there were in 1910 refers to all apples produced in 1910, regardless of location. E is illogical: since that refers to a doubling, E nonsensically asserts that the doubling occurred in 1910.

但是也有补出实意动词的：

92. Never before had taxpayers confronted so many changes at once as they had in the Tax Reform Act of 1986.
(A) so many changes at once as they had in
(B) at once as many changes as
(C) at once as many changes that there were with
(D) as many changes at once as they confronted in
(E) so many changes at once that confronted them in
Choice D is the best answer, stating grammatically and clearly that, with the 1986 Tax Reform Act, taxpayers confronted more simultaneous changes than ever before. In choice A, the past perfect had [confronted] illogically places the 1986 events in the same time frame as Never before had...; a simple past tense is needed to present the 1986 events as following the earlier ones. Choices B and C awkwardly place at once between confronted and its direct object, changes. Furthermore, B illogically states that the Act itself was many changes, when the point is rather that it presented many changes, and as many ... that is an unidiomatic comparison. Choice E, too, presents an unidiomatic comparison with so many... that.

这一点建议不要用作排除。

both of them are right

积极消化中～不过lz那道题我还有个疑问：为什么是less of a commitment，这个比较用法不懂，less of有什么固定含义吗？

希望NN指导

这个是主谓+介宾结构的主语比较结构

young people
            have
            less of a commitment to work and a career
            than
            their parents and grandparents
            had

OG 例题：

例 OG224： 主语比较_主谓+介宾句型
Inuits of the Bering Sea 和 Aleuts or Inuits of the North Pacific and northern Alaska 比较；补出were，防止Aleuts or Inuits of the North Pacific and northern Alaska.和介宾结构中的contact with Europeans 比较。

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
The phrasing of the comparisons in choices A, B, and E is incomplete, so the comparisons are ambiguous: because longer than could be followed by either from or were, it is unclear whether Inuits of the Bering Sea were isolated from Europeans longer than from the other Native American groups, or whether they were isolated from Europeans longer than the other groups were. In A and C, in isolation from contact is wordy and unidiomatic. The awkward phrasing of E further distorts the sense of the sentence: because with cannot idiomatically serve as the preposition for in isolation, the sentence suggests that the Bering Sea Inuits were totally isolated. Choice D is best: it employs concise, idiomatc phrasing to express a logically complete comparison.