Question

How to use these words in spoken english in correct way ?? modals are always confusing like "must and should", "must and ought to" ,"can and could" ,"may and might".

Answer 1

"Must" is like something is really required, 100% needed to have done. MUST = HAVE TO, but not always:

I must = I think inside I need to do this (inside order)

I have to = it is told me to do (outside order)

 

Should - "You should wash your nose, it's dirty" is like an advice to do something.

Should = ought to

 

Notice also
Present: MUST, but past - had to

Presend: HAVE TO, and past - also had to.

Can is present tense, could - past.

Difference between could and would:

The rate is amount of politeness:

Can < Could < May < Would

Could is in questions really polite, but it is also (see above) past form of "can".

Would is the most polite way of asking, supposing and everything.

It would be a pleasure.

Would it have been Alex?

I was wondering wheter you would open the windows.

 

Excuse my typos, I answer on phone.