题目内容
2.According to the report,the number of animals used in experiments _______ by 30% over the years.( )A. | was reduced | B. | has been reduced | ||
C. | were reduced | D. | have been reduced |
分析 根据报告,试验中用到的动物的数量在这些年中减少了30%.
解答 答案:B
解析:"the number of+可数名词复数"作主语时其后的谓语动词用单数形式,故C、D选项直接排除;又根据句末的over the years"在这些年中"可知本题该使用现在完成时,故C选项排除.综上,只有B选项符合句意及用法.拓展:reduce by 意为"减少了…",reduce to意为"减少到…".
点评 本题考查现在完成时的被动语态,做此类题目时一定要仔细分析句子结构,根据语法及句意确定相应的时态与语态,再结合所给选项选出正确答案.

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