Great changes____ in our country during the past 20 years.A.have happened B.happened c.have been happened D.were happened为什么

分类: 作业答案 • 2021-12-19 17:08:46

问题描述：

Great changes____ in our country during the past 20 years.
A.have happened B.happened c.have been happened D.were happened
为什么

答

A吧这个during the past 20 years是过去完成的标志

答

选A
因为happen没有被动,所以C和D被排除
during the past 20 years是过去的一段时间
过去时不能表示这一意思
完成时可以表示
所以选A