一、省略結(jié)構(gòu)分析

　　The guiding principles of the tax plan released by the Treasury Department could have even a greater significance for the economy than the particulars of the plan.

　　(A) even a greater significance for the economy than

　　(B) a significance that is even greater for the economy than

　　(C) even greater significance for the economy than have

　　(D) even greater significance for the economy than do

　　(E) a significance even greater for the economy than have

　　考察比較中的省略結(jié)構(gòu)。

　　也就是than后面到底是沒有助動詞，還是加do,或者是have。首先than后面如果有助動詞的話，必然是事情和事情的比較，也就是句子間的比較，GMAT語法如果沒有助動詞就是than前后名詞的比較。GMAT考試Do 和have的取舍在于前面的時態(tài)，如果前面是一般時態(tài)就用do的形式，如果前面是完成時就用have的形式。

　　這里很顯然是事情和事情的比較(principles 和particulars各自have significance的比較)所以需要助動詞，因為前面是一般時態(tài)，GMAT入門生都知道所以用do,選擇D

　　另外，significance是不可數(shù)名詞。

　　二、after的妙用

　　1 after doing 相關(guān)問題

　　220. (GWD-24-8, OG12-86)The results of the company's cost-cuttingmeasures are evident in its profits, which increased five percent during thefirst three months of this year after it fell over the last two years.

　　A. whichincreased five percent during the first three months of this year after it fell

　　B. whichhad increased five percent during the first three months of this year after ithad fallen

　　C. whichhave increased five percent during the first three months of this year afterfalling

　　D. with a five percent increase during the firstthree months of this year after falling (C)

　　E. with a five percent increase during the firstthree months of this year after having fallen

　　答案選C，但解釋上有點問題我不明白：下面是語GMAT語法筆記上對于B和C的解釋：

　　B. after it had fallen時態(tài)上沒有問題，可以與over the last two years搭配，但是不如after falling簡潔

　　C. Correct;afterfalling簡潔，狀語從句的省略

　　求助GMAT考試討論：可是我不理解為什把after doing理解為狀語從句的省略。我覺得這里不是省略!!!

　　狀語從句的省略：從句主語和主句主語一致，并且包含be。。。從句主語和be可以省略。when，although ，等詞引導(dǎo)時間狀語從句，讓步狀語從句等時，可以用這種形式來簡潔表達。

　　但是如果把這里的after doing 理解為 after it have/had been falling。我覺得也不能清晰的表達出原文所想表達的時態(tài)先后關(guān)系。而且如果這里 fall是進行時表達一直在下降，這里也是不對的吧。