Remember that one of the defining characteristics of modals is that they can't function as infinitives. If you bear that in mind, it helps you predict the impossibility of what you are suggesting and similar sentnces.

So, the solution is that you need to find another periphrastic construct (usually "need to" or "have to" etc) with a similar meaning.

Remember that one of the defining characteristics of modals is that they can't function as infinitives. If you bear that in mind, it helps you predict the impossibility of what you are suggesting and similar sentences.

So, the solution is that you need to find another periphrastic construct (usually "need to" or "have to" etc) with a similar meaning.