For many online shops the price of their products can be decreased 30% in the holiday se

问题补充：

For many online shops, the price of their products can be decreased 30% in the holiday seasons.

A. to

B. of

C. by

D. on

答案：

A. to

B. of

(答案→)C. by

D. on

解析：句意：对于许多网店来说，在假日他们产品的价格会减少30%。To为了；of属于……的；by相差；on在……上，选C。