The goods _______ shipped already if your L/C had arrived by the

The goods _______ shipped already if your L/C had arrived by the end of December.
A、would be
B、must have
C、had been
D、would have been
【正确答案】：D
【题目解析】：if引导的虚拟语气，从句用had+done，主句要用would have done表示对过去的虚拟。
句意：如果你方信用证在12月底之前到达，货物就已经装运了。