英语时态题
----MayIspeaktoyourmanagerMrWilliamsatfiveo'clocktonight?
----I'msorry.MrWilliams_____toaconferencelongbeforethen.
A.hadgone
B.hasgone
C.wouldhavegone
D.willhavegone
(请写出分析,还有longbeforethen应该怎么翻译?)