A new technique______ the yields as a whole increased by 20 percent since last year.A．wor
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A new technique______, the yields as a whole increased by 20 percent since last year.
A．working out
B．having worked out
C．having been worked out
D．to have been worked out
请帮忙给出正确答案和分析，谢谢！
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正确答案：C
本题考查非谓语动词，选项中workout的意思是“作出、推出”。全句意思是：“新技术推出以后，总产量从去年起增加了20％。”从结构来看，逗号前应是一个分词独立结构，作句子的状语(本句中表示原因)。tohavebeenworkedout中用的是动词不定式，所以选项D不是答案；动词workout是及物动词，newtechnique(新技术)是workout的动作对象，所以要用被动态语态，而选项A和B都是主动语态，都不可能是答案。workout这一动作发生在本句谓语动词的动作之前，应该用现在分词完成式的被动语态。所以havingbeenworkedout是答案。全句相当于：Asanewtechniquehadbeenworkedout，theyieldsasawholeincreasedby20percentsincelastyear．