Arguing with a 3Year Old

Evelyn: Mummy,  today I had chippies and nuggets from KFC
Mummy: Did you keep any for me?
Evelyn: No...
Mummy: *showing sad face* How come you didn't keep any for me?

Thinks for a while
Evelyn: You was at work!!
Mummy: But you could have kept for me....
Evelyn: But you was at work!!!!
Mummy: You could have kept until I came back
Evelyn: Who ask you to come back so late???

How do I answer such a question? And yet you were not done:
Evelyn: You already ate biscuit with frosting and chocolate!!

OooOoo... really lost this time.

Evelyn 1, Mummy 0