7.     

Obtaining an investment-grade rating will keep the county's future borrowing costs low, protect its already-tattered image, and increase its ability to buy bond insurance.

(A) Obtaining an investment-grade rating will keep the county's future borrowing costs low, protect

(B) To obtain an investment-grade rating will keep the county's future borrowing costs low, and protect

(C) Having obtained an investment-grade rating will, in keeping the county's future borrowing costs low, protect

(D) To obtain an investment-grade rating would keep the county's future borrowing costs low, protecting

(E) Obtaining an investment-grade rating, keeping the county's borrowing costs low, would be protecting

另外再说一下这几天做prep的感受，似乎跟BY在侧重方面有很多不同，BY更强调语法

的硬知识，而prep貌似更讲究句子的逻辑性，逻辑至上，甚至为了逻辑可以改情态，添新

词。不知道我这么说对不对。

根据谓语的平行排除，就只剩下A了。

its指代the country's。

不是逻辑主语，句子为动名词作主语的典型的主谓宾结构。

有同感，做大全觉得大部分不难，还很省时间。遇到了固定搭配不会就是不会，记住就行了。做gwd已经感觉有侧重不同的地方了，强调了那么一点点逻辑感和比较出正确答案。刚开始做prep超级不适应，剩下的选项貌似没有致命的语法硬伤，只能根据逻辑意思的合理性来排除。比如出现一个代词时也可能因为逻辑指代和语法指代不一样导致错误。一个很完美的平行结构可能因为意思上是伴随或结果关系而只能改成分词形式。

不知道实战的语法是什么感觉的，有战过的人说说吗？