1. I'm sorry that... [ex. I was so rude yesterday]
2. It's my fault. (= I am taking responsibility for the problem)
3. Oops, sorry.
(for very small problems)
4. I should have... [ex. called you and told you I'd be late]
5. (formal) I apologize for... [ex. the delay]

Fact
Studies show that couples that smoke during the time of conception have a higher chance of having a girl compared to couples that do not smoke      .. More >>