OG 101

Even though the direct costs of malpractice disputes amounts to a sum lower than one percent of the $541 billion the nation spent on health care last year, doctors say fear of lawsuits plays a major role in health-care inflation.

(A) amounts to a sum lower

(B) amounts to less

(C) amounted to less

(D) amounted to lower

(E) amounted to a lower sum

答案是C，对于OG的解释，我想不通。OG里面说：“In D, the adjective lower is erroneously used in place of the noun less as object of the preposition to. ”我的问题是：

1，less有名词形式吗？

2，costs是可数名词，怎么可以用less来修饰呢？

请各位指点。谢谢。

1、LESS有名词形式：http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=49592&page=2

2、less than one percent， less than 一个词组用来修饰one percent.

补充：amount to本身就有sum的意思在里，后面再出现sum显累赘~~