According to Oxford Dictionaries Online,
finite ... 2 Grammar (of a verb form) having a specific tense, number, and person.
non-finite ... Grammar (of a verb form) not limited by tense, person, or number.
Modal verbs (can, may, should etc) are always followed by bare infinitives. For example:
We could practice our dialogue.
Here, practice is a bare infinitive and is a non-finite verb and can, by its own nature, does not express tense, person or number.
Does that imply that in sentences like the one above, where a bare infinitive follows a modal verb, neither is a finite verb? If so, am I correct in understanding that we can have grammatically legitimate clauses and sentences even without a finite verb?