Clauses are groups of words which express an idea and contain a predicate (i.e., a conjugated verb) and a subject, although of course in Spanish the subject is often merely indicated by the verb ending. They can be divided into two categories: independent clauses (which make sense in and of themselves) and dependent clauses (which need to be used with an independent clause to form a complete sentece). In general, the the indicative, the conditional, and the imperative (command forms) are used in independent clauses; some exceptions will be given in section I below. The subjunctive mood is found primarily in dependent clauses, but of course the other moods can occur there as well, depending on the type of clause, the action/state involved, and its relationship to other elements in the sentences such as the governing verb.
Use of the subjunctive in independent clauses. As already mentioned, the subjunctive is seldom used in main clauses, but there are a few exceptions:
The past subjunctive may be used with the verbs poder, querer, and deber to express courtesy or an attitude of deference.
(Yo) quisiera pedirte un favor.I 'd like to ask you a favor.
Debieras practicar un poco más.You should practice a little more.
¿Pudieran Uds. darme otros ejemplos?Could you give me some other examples?
Words meaning “perhaps” (tal vez, quizá, and quizás) may be followed by the subjunctive to suggest that the action or state is improbable, or doubtful; they may also be followed by the indicative to stress a greater degree of likelihood or probability. [Note: The expression for “perhaps” has no effect on the verb if it comes after the verb.]
Quizás participamos en la fiesta.Perhaps we 'll take part in the festival.[Indic.: probable]
Quizás participemos en la fiesta.Perhaps we 'll take part in the festival.[Subj.: doubtful]
Command forms —or imperatives— are based on the subjunctive, with only three