题目：
Your teacher ________ very angry at that moment because you talked back to her like that.
A．should have been
B．must have been
C．must be
D．might have been
答案：
答案：B
B 考察情态动词。由语境可知。你那样对老师说话。想必他一定很生气。Should have done过去本应该做某事…实际上却未做；,must have done一定做了某事；might have done也许已经…；根据at the moment和talked可知此处是对过去事情的猜测，排除C项。由语境可知B正确。
