prices we have to take into consideration the quality of the goods . A. While comparedB

问题补充：

prices , we have to take into consideration the quality of the goods .

A. While compared

B. Compared

C. Compare

D. When comparing

答案：

A. While compared

B. Compared

C. Compare

(答案→)D. When comparing

解析：句意：当对比价格的时候，我们要考虑商品的质量。这句话是省略句，完整的句子是：When we are comparing prices，we have…，当主从句的主语一致的时候，可以省略从句中的主语和be动词，所以选D。