问题
What did you say to Julia Isaw her crying in the dormitory alone. — It ______ my fault. We talkedhappily when I was with her in the classroom.
A:mustn’thave been
B:should have been
C:shouldn’t have been
D:couldn’t have been
B:should have been
C:shouldn’t have been
D:couldn’t have been
正确答案是：
