In Britain sales of cigarettes have been reduced 30% in the past ten years.A. forB. toC

问题补充：

In Britain,sales of cigarettes have been reduced 30% in the past ten years.

A. for

B. to

C. from

D. by

答案：

A. for

B. to

C. from

(答案→)D. by

解析：to表示增加、减少、降低到什么程度,一般包括底数在内。by表示增加或减少的净数,不包括底数,常可省略。句意:在英国,过去十年中,烟的销量下降了30%。