| Usage | Modal Verb | Example |
| No choice – you have to do this | Must / have to | As citizens we must obey the laws of the country in which we live. |
| No choice – you cannot do this | Must not /not be allowed to / cannot | Citizens must not break the laws of the society in which they live. |
| Recommended – you should do this | Should / Ought to | Students choosing to study post-graduate programmes should fund their own education costs. |
| Recommended – you should not do this | Should not / Ought not to | Children should not argue with adults. |
| You can choose to do this if you want to | To be allowed to/can/ | Many children are allowed to watch television whenever they want to. |
| You can choose not to do this if you want to | Need not / do not need to / do not have to | In Britain, motorists do not need to carry their driving licence with them when driving their cars, which is quite unusual. |
| Needs and necessities | Need to | We need to find a solution to problems of poverty in the developing world. |
