Great changes______ in our country since 1980.

填have taken place
因为take place（发生vt.）的主语就是动作发出者本身,没有被动的说法.例如：昨天在这发生了一场地震 An earthquake took place here.
类似的动词：taste,It tasts good.(它尝起来不错),它是“被尝”,但也不用被动,依然是主动.