It often shows us that the obligation comes from the speaker (or the authority that wrote the sentence). Must expresses a strong obligation or necessity. We sometimes call this 'external obligation'. (Student to teacher) When do we have to hand in our homework?Īl has to work tomorrow so he can't come. We have to wear a uniform when we're working in reception. Have to shows us that the obligation comes from outside the speaker. There is a slight difference between the way we use them. We use have to and must to express obligation.

(Teacher to student) You mustn't be late to class. (Parent to child) You mustn't say things like that to your sister.

We use mustn't particularly when the prohibition comes from the speaker. Visitors must not park in the staff car park. It is common on public signs and notices informing people of rules and laws. We use must not to talk about what is not permitted. Sorry, we can't sell knives to under-18s. What does this sign say? Oh, we can't park here. We use can't to talk about something that is against the rules, particularly when we didn't make the rules. We use can't and mustn't to show that something is prohibited – it is not allowed. These pages may be photocopied for classroom use. May is the most formal way to ask for and give permission.Ĭustomers may request a refund within a period of 30 days. Could is more formal and polite than can.Ĭould I borrow your pen for a moment, please? may We also use could to ask for permission (but not to give it). We often use can to ask for and give permission. We often use verbs with modal meanings to talk about permission and obligation. Modals – permission and obligation: Grammar test 1 You don't have to have a licence to cycle on the roads. You have to have a licence to drive a car. I must call the electrician and get that light fixed. You can put your shoes and coat over there. Look at these examples to see how can, can't, must, mustn't, have to and don’t have to are used.

Modal verbs exercises pdf