请教分词以及不定式做主语的逻辑主语～～～～～～～～～～～～～～

henry1126

prep－7

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

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

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

(C) Having obtained aninvestment-grade rating will, in keeping the county's future borrowing costslow, protect

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

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

Ans：A

请问，这里分词和不定式作主语，它的逻辑主语应该是什么，如何判断～～～谢谢！！！！（请忽略其它的语法错误，只针对上面这个问题）

tianlingfrl

本题没有逻辑主语 主语就是Obtaining aninvestment-grade rating
例如Claimbing mountain is interesting~爬山是很有趣的~
如果要找逻辑主语，应该往后看，有没有动作的施受人，及动作是谁发出的，或动作是谁承受的，同时要考虑该动作的施受人是否合理，比如只有人物才能提出某种概念~而且带逻辑主语的分词和不定式结构，往往是作为伴随状语，修饰主语的z作用来出现~所以看句子里有没有主语就行了~
我一般就是这么判断的~动作有时候不一定后面要跟主语，中文里也有这样的结构，吸烟有害健康，主语就是吸烟，谓语是有害，宾语就是健康~不需要逻辑主语~也就是说，除了人和物，动作也可以单独作为主语出现~

henry1126

谢谢NN！！！实际上就是说这里的动作都是泛指，是吧～～～