Modals of Certainty - Must, Can't and Couldn't - Learn English Grammar

Thank you.
You know that you are My,My Teacher 🤗🤗
I want you to live long and healthy.

Hey,is not could the simple past of can

We can use "must not" for a locigal conclusion.

Misophonia alert. Great video though.

Ma'am ,
can we not use must not+ have+ past participle in any case??
for ex- "You must not have heard this"
please reply

If you are sure something is not true, you can say "can't be" or "couldn't be" as a modal, right?
Are these interchangeable in terms of modal of certainty?
For instance, we can say "It can't be mine" or "It couldn't be mine."

I think you have very clear English because I can understand you and I am not good at listening without my own native language subtitles.

What is the meaning of "be going to happen"?

What is the meaning of "likely to happen "?