must would

You cannot use two modals together. If you actually did the work, you can say "I had to do the work before today". If you did not do it, say "I should have done the work before today".

Thank you very much.
And I too could say, I must have done the work before today, yes?

khoshtip I too could say, I must have done the work before today, yes?

Only if you want to say that this is a logical deduction from the facts to hand. It's a very unlikely utterance with a first person subject.

khoshtipI must have done the work before today

Do you mean the following, perhaps?

I must have the work done before the end of the day (today).
(I am required to finish the work before the day ends.)

CJ

Yes, I mean things like this. So saying it is OK.

khoshtipYes, I mean things like this. So saying it is OK.

It depends on what "it" is. You can say I must have the work done before the end of the day today, but you can't say anything with must would.

CJ

Thank you. No, I will never use must + would.
The discussion would refer more to the differences between the should and must in those sentences.

khoshtipthe differences between the should and must

I should have the work done by the end of the day.

1. It would be a good idea for me to have the work done by the end of the day.
It is advisable for me to have the work done by the end of the day.

2. I expect to have the work done by the end of the day.

Only the larger

Thank you very much CJ.