大全 987-858 很绕的题目 无讨论

958.    There is substantial evidence that certain forms of solar energy either now or within a few years will be economically competitive with conventional sources of heat and power.

(A) either now or within a few years will be economically competitive with conventional sources of heat and power

(B) will either be economically competitive with conventional sources of heat and power within a few years or are so now

(C) will be economically competitive with conventional sources of heat and power either now or within a few years

(D) either are now economically competitive with conventional sources of heat and power or will be so within a few years（D）

(E) are either now or will be within a few years economically competitive with conventional sources of heat and power

这道题目either, or是修饰时间的，为什么不能选c呢？

狂不明白 求教

either now or within a few years表示现在或者将来，因此要配合两个不同的时态，一般现在和将来，A/C均只使用了将来时，有问题排除。这体现了GMAT对句子逻辑严谨的要求。

另外提供你一个方法：看到now/a few years表示时间，通过句子意思理解是做时间状语来修饰谓语，一定要注意它们的放置位置是有严格要求的。通常不能放在助动词之前，而需要放在助动词之后或表意思动词之后，通过这个就可以把A/E排除，然后利用平行原则，把B/C排除，选D