I would have gone with you, but I （）too tired.
A、
was
B、
had been
C、
must be
D、
must have been
【正确答案】：A
【题目解析】：
时态，“我本来应该跟你走的，但是我太累了”would have done是对过去的虚拟，所以，后面表示真实原因，也应用过去式was.
I would have gone with you, but I （）too tired.
I would have gone with you, but I （）too tired.
was
had been
must be
must have been
时态，“我本来应该跟你走的，但是我太累了”would have done是对过去的虚拟，所以，后面表示真实原因，也应用过去式was.