How to use modal verbs Must, Have, and Should

This English lesson is about how to use the modal verbs Must, Have, Should. It is important to know how to use these verbs correctly. This lesson will show you how. 

We use must and have (to) fairly similarly. Should and must are also similar, so they can be a bit confusing for people learning English. 

Should

Look at this sentence:

You look terrible. You should see a doctor. 

In this sentence I think that it is a good idea for that person to see a doctor based on what I can see. I am giving them my advice. 

We could also use ‘must‘ – ‘You must see a doctor’, but this would only be in an extreme case. It is a lot stronger to use ‘must’ here. If you thought the person’s life was in danger, then ‘must’ is the better option. 

Another example: 

You should live in an English-speaking country if you want to perfect your English. 

Again, I am giving you my advice. I think that it is the best thing to do if you want to improve your English level. 

Must

Let’s look at how we use must. Take a look at this example sentence: 

I must remember to renew my passport. I have to travel overseas in September. 

Here the obligation is on me to remember to renew my passport. If not, I won’t be able to travel. 

Another example: 

The judge told him that he must not get into more trouble or he will be sent to prison. 

The judge has put that condition on him. He has been warned to stay out of trouble. 

Have (to)

Remember that must and have to are very similar. In fact, you can easily substitute one for the other in many cases. 

However, there is a slight difference in meaning. Look at the following example:

I can’t come to the party. I have to see a man about a dog. 

Whether we use have to or must usually depends on where the obligation to do something comes from. In the above sentence I have arranged to see a man about a dog, so have to is the best option. 

In this sentence both can be used. 

If you go to Granada, you must/have to visit the Alhambra.