To improve the quality of our products we asks for suggestions had used the products.A. w

问题补充：

To improve the quality of our products ,we asks for suggestions had used the products.

A. whoever

B. who

C. whichever

D. which

答案：

(答案→)A. whoever

B. who

C. whichever

D. which

解析：whoever had used the products 使用过产品的任何人，作asks的宾语从句，从句较长，所以后置。