Learn more about Grammar:
Adjectives: An Easy Guide with ExamplesAdverbial Clauses: What Are They?AdverbsAnalogy: Definition & Meaning (with Examples)ArticlesBad AdverbsClauses: Definition, Meaning, and How to Use ThemConjunctionsCoordinating Conjunctions: What Are They and When Should You Use Them?Dangling ModifiersDeclarative Sentence: Examples + MeaningExaggerationHomophones: Definition and ExamplesHow to Use Subordinating ConjunctionsInfinitivesInterjections: Definition, Meaning, and ExamplesIntransitive Verb: Definition, Meaning, and ExamplesNounsParticiples PluralsPrepositional Phrase: What Is It & How to UsePrepositionsSplit Infinitive: The Complete Guide (with Examples)Subordinate Clause: Definition, Types, and ExamplesThe Complete Guide to Transitive VerbsTransitions: A Complete Guide (with 100+ Examples)Types of VerbsVerbsWhat is a Pronoun? Rules and ExamplesWhat Is Symbolism in Writing?Word ClassesWhat are modal verbs? How do you use them?

Modal verbs (can, could, may, might, will, shall, would, should and must) are followed by the bare infinitive:
I could hear the dog barking outside.
You must be joking.
He may have caught the train.
You should have told me earlier.
Be careful when choosing between the modal verb 'should' and the word 'ought', because they have the same meaning but different grammar. Ought is followed by a to-infinitive:
You ought to know that by now.
They ought to have insisted on some compensation.