Talking about Necessity

Some structures in English imply something that is not optional and there is a need to do them.

How to "Talk about Necessity" In English?

What Do We Mean by 'Necessity'?

When we say 'necessity' we refer to something that needs to be done. In English, there are some words that help you give orders, whether to yourself or to others. Here are the words that are used to express necessity in English:

Using 'Must'

The modal verb 'must' can be used to express necessity and obligation. It expresses a strong obligation. It is mostly used in formal writings.
As you know, 'must' as a modal verb is followed by an infinitive without to (bare infinitive). 'Must' can refer to both present and future.

You must be there on time. Ok?

I must study today. Let's go out tomorrow.

Making Questions

Usually, we do not use the question form of the modal verb 'must.' But if you want to make questions with 'must,' you must use modal verb. It means that you have to use 'must' before the subject.

Must I finish it by 10 pm?

Must they fasten their seat belts?

Using 'Have to'

Another way to express necessity and obligation is to use 'have to.' Using 'have to' is more common in English. And it is important to know that there is a bare infinitive used after have to.

You have to clean the house.

In some religions girls have to wear scarves.

Making Questions

Actually, using 'have to' in interrogative sentences is very common. The only thing you have to be really cautious about is to use the auxiliary verbs (do, does, did), based on the tense of the interrogative sentences.

Do we have to wait for him?

Did he have to write five articles in one day back then?

Using 'Have Got to'

One of the ways to express obligation and necessity is to use the phrase 'have got to'. This structure is actually more common in informal contexts or conversations. Remember, the verb after have got to must be a 'bare infinitive.'

Look who has got to give some presents!

I have got to go. There is a party at 7.

Making Questions

As the verb 'have' in the phrase 'have got to' is an auxiliary, to make a question, all we have to do is to invert the subject and the auxiliary verb 'have.'

Has she got to pick up John from school?

Have you got to set up the blind date for them?

using 'have to' to talk about necessities

Using 'Need to'

The verb need can be used as either a helping verb or a main verb. In both cases, it can express necessity and obligation. Using the affirmative form of the helping verb 'need' is not common in English.
Grammarians tend to use the negative form though.

You need to send all the emails within two days.

I need to take a shower before sleep every night.


'Need' as a main verb is followed by a to-infinitive, but as a helping verb, it is followed by a 'bare infinitive.'

Making Questions

If we consider 'need' a main verb, as the general rule requires, we have to add the helping verbs (do, does, did) to the beginning of the sentence to make an interrogative sentence.
If we consider 'need' the helping verb, all we need to do is to follow the inversion rule and put the helping verb at the beginning of the sentence

Do we need to drink all the milk Mummy?

Need I be worry for you, or you have everything under control?

Using 'Shall'

'Shall' is a modal verb that can be used to describe formal obligation. By formal obligation, we mean 'documents' or 'official contexts.' This structure is normally used to give guidelines to people.

You shall pay the rent at the beginning of the month.

He shall start giving the speech, the public is waiting for him.

Making Questions

Since 'shall' is a modal verb making questions by it is too easy. All you need to do is to put the modal verb at the beginning of the sentence. In other words, you use the inversion and change the place of the modal verb and the subject.

Shall I submit the email to the boss?

Shall he answer the phone calls?

'Must' vs. 'Have to'

Actually, both these terms are considered the same in speaking, but when it comes to rules and grammar, 'must' is used for internal necessity.
We mean things that you yourself chose to be an obligation for yourself unless we are talking about official documents or notices that are external obligations.

I must clean up my room. It is really messy.

You must confirm your name before entering Miss.

'Have to' is usually used for things that are externally necessary. It refers to rules and laws. In this case, orders that are expressed by 'have to' are really strict.

Sir! You have to wear your mask, because of the Corona virus.

Maria has to submit her homework by the mentioned deadline.

Necessity and Obligation: Past Tense

Had to

It is important to know that there is no past form for the modal verb 'must' in English. On the other hand, a past form for the phrase 'have got to' does not exist.
In this case, the past tense form for (have to, must, and have got to) is the phrase 'had to.'

We had to be on time for the meeting.

The plane had to take off immediately.


'Should' is the past tense of the modal verb 'shall', but we cannot say that it functions exactly like the verb 'shall' in past form. Actually, 'should' can be also used to express 'obligation,' but this is usually the 'moral obligation' not something 'mandatory.'

I should pay more attention.

We should take her to the hospital.

If there is a strong obligation, you can use 'had to' instead of 'should'.

Needed (to)

The past tense of the verb 'need' is 'needed' whether main verb or helping verb. And by all means, we use it to talk about past obligations. Remember, using 'need' as a helping verb in affirmative form is not common at all.

I needed to stop there to buy some stuff.

Anna and Pam needed to answer two questions, each.


Using 'Not' after the Verbs

Among the verbs that we have mentioned, (shall, should, must, have got to, need) can be negated by adding the term 'not' to the auxiliary part of them. Check out the examples for clarification:

You must not do workout when your muscles are weak.

You needn't worry for him anymore, he turned thirty last year.

She hasn't got to complete the essay, that is Sara's duty.

Negative Markers and Needn't

As you might know, 'negative markers' are not usually used with negative verbs, because they make 'double negation,' which is considered wrong in English grammar.
But when it comes to 'need not' grammarians tend to use 'negative markers' and it is surprisingly considered correct.

Nobody needn't wait for me! Have your meals, I will be late.

Using Helping Verbs

'Have to' and 'need' as the main verb need helping verbs [do, does, did] to be added by the term 'not' to make them negative. Here are some examples to be considered.

You did not have to do my dishes.

She didn't need to work. Her father was a merchant.

'Must not' vs. 'Do Not Have to'

  • 'Must not' is used to indicate that something is important not to be done or happen.

Harry must not waste any more minutes.

Holter must not know her secret.

  • 'Do not have to' is used to refer to something that is not obligation or necessity, and it is optional for you to do it or not.

You do not have to wear a coat. It is not that cold here.

Do we have to buy presents for her new house?

To Be Supposed to

'To be supposed to do something' is an expression that is used to say that we need to do something or something has to be done. To change the tense of the sentences you have to change the tense of the verb be. Check out the examples for clarification:

She is supposed to be here at 10.

I was supposed to fill up the car.

Using 'Had to Have'

You can use the past tense of have to (had to) before (have + past participle) To talk about things that needed to be done but in some cases, they may have happened or not. Check out the examples:

I had to have studied more to enter that university.

I had to have done all the laundry.

Using 'Should Have'

You can use the phrase 'should have' before 'past participles' to express things that were supposed to be done, but in some cases, they did not happen and now you somehow regret it.

I should have seen him before it was too late.

Marry should have waited for me to pick her up.


There are some verbs and verb phrases that are used to talk about necessity. Here are the verbs.

  • must
  • have to
  • have got to
  • need (to)
  • shall


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