1. Phrase 1 is a general short apology. We use this when we bump into people on the street. At other times, it sounds too weak.
2. In phrase 2, we use so very and terribly to make the meaning stronger. Terribly is the strongest. If we use one of the words in brackets, it is stressed.
3. Phrase 3 is quite formal but it s a stronger apology than just sorry
4. We use phrase 4 to criticise ourselves and the mistake that we have just made.
5. We use phrases 6 and 7 to take all the responsibility for what happened. Phrase 7 is a little stronger.
6.We use phrase 8 to apologise for our lack of knowledge or ability. We can replace the word in brackets with other nouns, e.g. carelessness, forgetfulness.
7. Phrase 9 is asking the other person not to get angry. The tone is quite informal.
8. Phrase 10 is often used in formal letters. The word sincerest makes the apology very strong and very formal