1. Rewrite the sentences by replacing the underlined expressions with the correct modal verb (couldn't, can, need, needn't, ought to, must). Make the necessary changes. 1 Richard has the ability to solve maths problems very quickly. Richard __________ 2 It isn't necessary to stay in the exam hall after you have completed the test. You __________ 3 I advise you to seek help if you are having problems understanding something. You __________ 4 Nia is a very well-behaved child. I doubt that she was nasty to the other children. Nia is a very well-behaved child. She __________ 5 It is necessary for you to have a computer password. You __________ 6 Students are obliged to be on time for class. Students __________

1. Richard can solve maths problems very quickly. 2. You needn't stay in the exam hall after you have completed the test. 3. You ought to seek help if you are having problems understanding something. 4. Nia is a very well-behaved child. She couldn't be nasty to the other children. 5. You must have a computer password. 6. Students must be on time for class. Объяснение: 1. *can* используется для выражения способности. 2. *needn't* используется, чтобы показать отсутствие необходимости. 3. *ought to* используется для выражения совета или рекомендации. 4. *couldn't* используется для выражения сомнения или неспособности в прошлом. 5. *must* используется для выражения необходимости или обязательства. 6. *must* используется для выражения обязательства.