--How long each other before they married?--For about a year.A. have they known;getB. did

问题补充：

--How long each other before they married?

--For about a year.

A. have they known;get

B. did they know; were going to get

C. do they know;are going to get

D. had they known; got

答案：

A. have they known;get

B. did they know; were going to get

C. do they know;are going to get

(答案→)D. had they known; got

解析：根据句意分析，他们结婚是已过去的事，那么，他们互相了解大约一年的时间肯定发生在结婚前，发生在过去某一动作之前的动作，应该使用过去完成时。