Modals of Necessity

• Must

• Have to/has to - had to (past)

• Need to​

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We use those modals and related expressions with the base form of a verb to talk about things that are necessary, required​ or responsibilities

Must

• the strongest

• most common in writing

• often used to talk about rules, laws, regulation

• It is unusual to use “must” in questions​

• used only in the present and future. Past form of must is had to​

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Have to​

• most common ​spoken and written

• ​It is useful for forming questions and negatives.

• have to​ and have got to mean the same. Have got to is more informal.

• ​The subject and verb must agree for he/she/it subjects AND the question form requires “Do/Does/Did”.

Example:

+ She has to study tonight / I have to wash the dishes

- She ​doesn't has to study tonight / I don't have to wash the dishes

? Does she has to study tonight?​ / Do I have to wash the dishes?

Need to

• things that are necessary to do in order to achieve a certain goal

• ​emphasizing the fact that it’s necessary​

Example:

I want to go to France, so I need to get a passport

​I need to finish this job by Friday

We need to study more if we want to get good grades

Negative

• "Don't have to," "don't need to" and "mustn't" have very different meanings

• ​"Don't have to" is used to express that something is not required

• ​"Don't need to" also expresses that a particular action is not necessary

• ​"Mustn't" is used to express that something is prohibited

Complete the sentences use modals of necessity!

1. Don ... (go) home early last night.

2. ​Children ... (play) with cleaning products.

3. ​We ... (get) going—it's already midnight!

4. ​They ... (visit) the doctor yesterday, as they were not feeling well.

5. ​She ... (worry) about her grades. She's a great student.

Try to answer it then check your answer to next slide.

1. Don had to go home early last night.

2. ​Children mustn't play with cleaning products.

3. ​We need to get going—it's already midnight!

4. ​They had to visit the doctor yesterday, as they were not feeling well.

5. ​She doesn't need to worry about her grades. She's a great student.