I am sorry that I broke the car.

[Hansman]

Is there a subtle difference in meaning between them?
1) I am sorry that I broke the car.
2) I am sorry, but I broke the car.
3) I am sorry! I broke the car.

Can I use them for the same meaning in the same situation?

 

[teechar]

I broke the car.

That's not natural, but for the sake of this question, let's say your sentence was "... I broke the vase".

Can I use them for the same meaning in the same situation?

Which meaning do you have in mind?
Note that #1 suggests the listener is already aware of the object being broken; the other two don't.

 

[jutfrank]

Whereas number 1 assumes the listener already knows that you broke the vase and is nothing more than an apology, numbers 2 and 3 by contrast inform the listener that you did it, and apologise at the same time.

 

[Hansman]

When do I have to use a comma or a period after 'I am sorry'?
I am sorry, I forgot.
I am sorry. I forgot.

I am sorry, I don't agree.
I am sorry. I don't agree.

What is the difference between them?

sorry adjective - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com

Definition of sorry adjective in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

www.oxfordlearnersdictionaries.com

 

[Tarheel]

When do I have to use a comma or a period after 'I am sorry'?
I am sorry, I forgot.
I am sorry. I forgot.

In both of those you are saying you are sorry you forgot. The comma or period indicates a natural pause.

 

[Tarheel]

I am sorry, I don't agree.
I am sorry. I don't agree.

That's a polite way of saying you disagree with somebody about something.

More natural would be:

Sorry, but I don't agree.

 

[jutfrank]

I'm both of those you are saying you are sorry you forgot. The comma or period indicates a natural pause.

That's not quite right. There is a difference in meaning:

1) I'm sorry. I forgot.

Here you're saying two things. You forgot to turn on the heating, for example, and now you're aplogising because your wife is cold. The sentence I forgot is an explanation of why you messed up.

2) I'm sorry (that) I forgot.

Here you're saying one thing. You forgot and now you regret forgetting. I asked you not to forget but you did.

In 1., you're apologising for not turning the heating on, and in 2. you're apologising for forgetting. That's not the same.

 

[Tarheel]

You're wrong. There's a comma in the first one. If it was "I'm sorry I forgot" that would be a different kettle of fish.

 

[jutfrank]

You're wrong. There's a comma in the first one. If it was "I'm sorry I forgot" that would be a different kettle of fish.

Oh, right, yes. Sorry, Tarheel.