2)
A: You did not tell me about the maths test.
B: I didn't know about it.
3)
A: You didn't buy me a present.
B: I didn't know about your birth day.
4)
A: You didn't send me a Christmas card.
B: I didn't have your address.
5)
A: You ate the sandwiches.
B: I was hungry.
6)
A: You didn't call me on my birthday.
B: I left my mobile at home.