Costshave

问题详情：

Costs have ________ 20% over the past years.

A．reduced by                        B．been reduced by

C．reducing to                       D．been reduced to

【回答】

B　reduce为及物动词，costs应为被减少，所以要用被动语态，排除A、C两项。另外“减少了”或“增加了”后面的百分数前要用介词by，to用在“减少到”或“增加到”后面的具体数字前。故B项正确。

知识点：动词

题型：选择题