1.Complete the sentences with a suitable modal verb. Use must, don’t have to, might, should, must have, mustn’t, can’t have and shouldn’t.
1. You drive on the pavement. It's illegal.
2. You say that. It's not nice.
3. I go to work tomorrow because it's a public holiday.
4. I buy this CD, but I'm not sure.
5. He's not here. He gone out.
6. She didn't study enough. She passed her exam.
7. You eat more vegetables. They're good for you.
8. You be 18 before you can buy alcohol.

1. You mustn't drive on the pavement. It's illegal. Explanation: Driving on the pavement is against the law, so it is necessary to use the modal verb "mustn't" to indicate that it is prohibited. 2. You shouldn't say that. It's not nice. Explanation: It is not polite or kind to say something like that, so the modal verb "shouldn't" is used to give advice or express a suggestion. 3. I don't have to go to work tomorrow because it's a public holiday. Explanation: Since it's a public holiday, there is no obligation or necessity to go to work, so the modal verb "don't have to" is used to indicate that something is not necessary. 4. I might buy this CD, but I'm not sure. Explanation: There is a possibility that I will buy the CD, but I am uncertain, so the modal verb "might" is used to express uncertainty or a possibility. 5. He can't have gone out. Explanation: It is impossible for him to have gone out because he is not here, so the modal verb "can't have" is used to indicate a strong belief or certainty in a negative way. 6. She must have not studied enough. She didn't pass her exam. Explanation: It is likely that she didn't study enough because she failed her exam, so the modal verb "must have" is used to suggest a strong possibility or likelihood of something happening in the past. 7. You should eat more vegetables. They're good for you. Explanation: Eating more vegetables is beneficial for your health, so the modal verb "should" is used to give advice or make a recommendation. 8. You must be 18 before you can buy alcohol. Explanation: It is necessary to be 18 years old in order to buy alcohol, so the modal verb "must" is used to indicate a strong requirement or obligation.