Usage of to be in sentence i.e. is/are/was/were to be, has/have/had to be

[Msudan]

Hi, I often confuse to use " to be " as well as "will be " I would be so grateful, if you will kindly describe them with examples.

[Yankee]

Hi msudan

Your question is really too general to be able to answer in a single post or thread. Can you make your question more specific, or give us some of examples of sentences that you find confusing?
.

[Msudan]

hi mam, Some examples are here.

It is to be completed by 4:00 pm
It has to be completed by 4:00 pm
It will be completed by 4:00
You have to do the work today itself.
You have to be done the work.

I actually would like to know as to when (at what stage) we use those sentence.

[Barb_D]

It is to be completed by 4:00 pm -- This is not a very likely sentence, although you can create a situation in which to use it.

It has to be completed by 4:00 pm -- A statement that expresses an obligation. "A: When does this need to be done? B: It has to be done by 4."

It will be completed by 4:00 -- A statement of certainty. You know that it will be finished by that time. "Okay then, if that's when you need it, I assure you, it will be completed by 4."

You have to do the work today itself. -- I'm not sure what "itself" means here. However, deleting that word, it tells the listener that he or she has an obligation to complete the work today.

You have to be done the work. -- This is not grammatical.