Apologising

Teacher - Hey, girls! hang on a minute.
Sue - Oh, no. I think we're in trouble.

Teacher - I saw you leave the computers on.
Tania - Oh, I'm really sorry. We forgot to turn them off.

Teacher - Well, can you remember next time, please?
Sue - Yes, of course.

Sue - OK. We didn't mean to cause a problem. We'll go and turn them off now.