第二节语法和词汇知识(共l5小题；每小题l分，满分l5分)
从A、B、C、D四个选项中，选出可以填人空白处的最佳选项，并在答题卡上将该项涂黑。
We_____last night，but we went to the concert instead．
A．must have studied     B．might study
C．should have studied   D．would study