单选题Great changes   &nbs

问题补充：

单选题GreatchangesinChinainthepast20years.A.took placeB.were taken placeC.have taken placeD.have been taken place

答案：

C解析考查时态，take place与happen这两个词没有被动语态，in the past 20 years表明应该用完成时态。故选C