请教763

1.                             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（D）

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

请问为什么不选c啊？

nn能不能详细讲讲助动词得问题啊？

谢谢～～

The guiding principles of the tax plan released by the Treasury Department could have even greater significance for the economy than do the particulars of the plan. fficeffice" />

stella131： Ecsniffer已经解释清楚了： “2、这里的do代替could have中的have，
助动词替代就是替代前面出现的相同动词，这里一般指的是行为动词。” Georgeqian也是说的这个意思。

Do是助动词提前构成than后面的倒装：

C简化为The guiding principles could have greater significance than do the particular items.

等于：The guiding principles could have greater significance than the particular items have.注意这里的have是实意动词而不是助动词，还是一般现在时。

如果用have代替do，The guiding principles could have greater significance than have the particular items. 等于The guiding principles could have greater significance than the particular items have had.变成了现在完成时，时态表达上不妥当。

同意d

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