‘I have to do an assignment on Romeo and Juliet, but I haven’t read it yet.’ ‘Well, you................ to start now if you want to get a good mark.’
have
‘His essays are copied off the Internet.’ ‘He................. do that. That’s called plagiarism.’
shouldn't
‘Do you know much about psychology?’ ‘I don’t, but you ...................ask Tom’s father, he’s a university professor.’
should