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

A.whacver                    B.who

C.whichever                  D.which

. To improve your spoken English, you’d better listen to the tape ______.

To improve your spoken English, you’d better listen to the tape ______.

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

To improve the quality of our products, we asked for suggestions _______ had used the product.