There are three moods in English: the indicative, used for facts, opinions, and questions; the imperative, used for orders or advice; and the subjunctive, used in certain contexts to express wishes, requests, or conditions contrary to fact.
Forms of the subjunctive
Uses of the subjunctive
Exercise: Verb tense and mood 1
Exercise: Verb tense and mood 2
Exercise: Verb tense and mood 3