--How long---each other before they---married?--For about a

--How long___each other before they___married?--For about a year.A.have they known;get B.did they--How long___each other before they___married?--For about a year.A.have they known;getB.did they know;getC.do they know;are going to getD.had they known;got为什么选D不选A?如果他们现在结的婚呢？