Grandpa Fionn's English Class

Some of you have been sending me pms to ask about English phrases or words. I think it might be good to share this so, here I am!
Years ago I was a teacher in a private school and I taught the fourth and fifth primary (elementari) It was a very 'interesting' experience!
Today's topic obligation
I must do my homework
I have to do my homework
I've got to do my homework - for pronunciation this sounds like 'I gotta do my homework
e.g. I gotta make a phone call to my best friends.
I gotta let them know that I'm leaving

CITAZIONE

When do I have to/must/gotta...(  ) use those phrases ? Examples and explanation , please !

'I have to/must/have got' to indicates obligation, something that it is necessary for you to do, either because there is some regulation that you need to respect ( I must arrive at work before 9 or my boss will be angry), or for some inner compulsion ( I must go on the forum as soon as I get home (I am really interested to see if someone has replied to my question)

Dear Tahti, I see you are from the old school!! My idea is not to do a detailed grammar analysis, I've seen too many students who know the English grammar perfectly but can't hold a conversation! Rather I wanted to help with basic problems of communication (after all, that's the primary purpose of a language!!)

CITAZIONE

what shall I say if I need to apologize for coughing...sorry or pardon me???

Excuse me!!

CITAZIONE

please fionn, if i made mistake......

If I make mistakes!!

CITAZIONE

Can you explain the use of have been + ing form , please?

Present perfect continuous used to describe an activity that started in the past and that you are still doing now or have just finished. it is different from the present perfect simple (I have done/seen etc.) because it emphasizes the continuity and duration of the action rather than the results achieved.
xamples:-
"I've been loving you too long to stop now" This love has been constant and has gone on for a long period.
"I've been waiting in the shadows all my life" A long wait (24 years!) and always in the shadows.
"I've been trying to find Ale Tohru's photo for one hour!" It's a long time and now I'm giving up