一个英语时态题目
问题描述：
一个英语时态题目
Floods and bad farming over the years ruined a land that ______ and made it miserably poor.
A.was once rich B.had once been rich C.have once been rich D.was once being rich
选哪个,详细讲下为什么
答
答案：B 解析：had been 发生在过去时（ruined）之前,故用过去完成时,如：He sang a song that had been popular for a long time.