How to use the words suppose, supposing, supposed to, have to, and ought to in English

If you want to presume something is true, you should only use the word suppose (without the d) as the present tense of the verb.
Although there is a risk that the subject won't carry out the main verb's action, the phrase (be) supposed to mean to do something" implies that the subject is required and anticipated to do so.
The magician is supposed to pull a rabbit out of his hat. A modal verb phrase with the meaning of expected or required contains the term supposed as part of it. Even while it should be used regularly in everyday speech and writing, that is not how it should be used.
Before stating a potential circumstance or course of action, you can use suppose or presuming. The customary next step is to think about what impact this circumstance or action might have.
Suppose someone gave you an egg and asked you to describe exactly what was inside. 
Supposing he's right and I do die tomorrow? Maybe I should take out an extra insurance policy.
The word be supposed to is a common phrase that functions in the same way as modal verbs. Modal verbs, also called auxiliary verbs, add meaning to the main verb in a sentence by expressing possibility, ability, permission, or obligation. The word supposed to, like have to, can be included in the category of "obligation".

Example:

I have to be home by midnight or my coach will turn into a pumpkin.

I am supposed to be home by midnight or my coach will turn into a pumpkin.

The verb to suppose

On the other hand, the verb to suppose means to assume, in theory, that something happened without any particular proof. 

Max isn’t here yet, so I suppose his train was delayed.

The committee supposes that the decline in profits is due to a faulty product design.

As a word meaning necessity, it can mean the equivalent of what would happen if.

Suppose my coach really does turn into a pumpkin. What will I do then?

The difference between supposed to, have to, and ought to

The modal verbs ought to, have to, and supposed to can cause confusion for some English language learners. All three words serve the same purpose in a statement, yet their meanings differ just a little.

The phrase "supposed to do something" emphasizes that the subject is required and anticipated to carry out the main verb's action, even when there is a possibility that it won't.

The magician is supposed to pull a rabbit out of his hat.

Although there is a chance that the magician will do the trick flawlessly in this instance, it is always possible that he won't. The reader must now wait to see if the hope expressed in the line will come true.

Has to and have to have the same meaning as must; they imply that the subject has no choice but to carry out the verb's action.

The magician has to produce the rabbit to earn applause.

This statement implies that there won't be any applause if the magician doesn't conjure a rabbit. To attain the outcome he desired, he just had to execute it.

Ought to is more of a recommendation. It indicates what the person is most capable of doing without pressuring them to.

The magician ought to slip his rabbit a carrot before the show.

The magician must always give his rabbit a carrot, even if no one asks him to, in order to make sure that he has a submissive and happy rabbit in his hat. That would be an excellent concept.

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