书名：国学新多益阅读题库解析
版本：2010(浅蓝色书皮)
页数：p.41 151题
题目：
Companies that are targeting this niche have found that products that simply do the job for _____ they were designed are easier to manufacture.
(A) what
(B) where
(C) which
(D) whom
疑问：正确答案是C，为什么不能用A