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.
1 Richard can solve maths problems very quickly.
2 It isn't necessary to stay in the exam hall after you have completed the test.
2 You needn't stay in the exam hall after you have completed the test.
3 I advise you to seek help if you are having problems understanding something.
3 You ought to seek help if you are having problems understanding something.
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.
4 She couldn't have been nasty to the other children.
5 It is necessary for you to have a computer password.
5 You need to have a computer password.
6 Students are obliged to be on time for class.
6 Students must be on time for class.
1 Richard has the ability to solve maths problems very quickly.
1 Richard can solve maths problems very quickly.
2 It isn't necessary to stay in the exam hall after you have completed the test.
2 You needn't stay in the exam hall after you have completed the test.
3 I advise you to seek help if you are having problems understanding something.
3 You ought to seek help if you are having problems understanding something.
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.
4 She couldn't have been nasty to the other children.
5 It is necessary for you to have a computer password.
5 You need to have a computer password.
6 Students are obliged to be on time for class.
6 Students must be on time for class.