I am an American teaching English to Spanish speakers in Venezuela. My students tend frequently to use "to" inappropriately and I'd like to be able to explain when it is appropriate and when not.
Examples of common mis-uses: I can to walk tomorrow. I will to cook dinner tonight.
He can't do go to school today.
I know the rules say not to use "to" after certain modals, but I can't find a good explanation of Modals or when you do not use "to" in other verb contexts. Can you help?