求问OG13小蓝本里的27题！！

lizzykin

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

这题根据平行选出A容易，但是有两处怎么都想不明白
1.不定式做主语和现在分词做主语有什么区别？
2. 为什么OG说：因为E选项中的keeping the country's borrowing costs low修饰了前面句子的主语就导致了increase缺少了主语呢？？
求大神解答！！！

lizzykin

求求求！！TT

老李同志

不定式：强调具体的、一次性的动作
现在分词：强调多次的、抽象的动作

e中 be protecting 和increase 不对称

lizzykin

老李同志 发表于 2015-5-10 10:03
不定式：强调具体的、一次性的动作
现在分词：强调多次的、抽象的动作

哦~~！！懂了！！！蟹蟹！！