Negative for 'must'

must not

Thank you! But if I write 'My father cannot but work for poor people', will it still be correct? This negative seems a logical one though preserving the meaning.

anonymousMy father must work for poor people.

"must work" is a modal expression. It contains the modal verb 'must' and the verb 'work'.

There are two ways to negate a modal expression. It depends whether you want to negate the modality or the residue. In the following discussion I assume you are using 'must' as 'have to', showing obligation.

M

So I should suppose the correct answer is either 'My father must not work for poor people' or 'My father need not work for poor people'. Thank you all.