The Subjunctive in Adjective Clauses

326. Adjective clauses, i.e., dependent clauses used after relative pronouns, have the verb in the subjunctive in the following cases:

a. When the antecedent clause expresses doubt, uncertainty, negation, condition.

Aquí no hay quien hable español. There is no one here who speaks Spanish.
No me dijo nada que me
pudiese convencer.
He did not tell me anything which could convince me.
No conozco a nadie que
lo pueda hacer.
I do not know any one who can
do it.

b. When indefiniteness or uncertainty is expressed in the relative clause itself.

Busco un criado que sepa trabajar. I am looking for a servant who can work.
Desean un dependiente que trabaje diez horas al día. They desire a clerk who will work ten hours a day.
No hagas lo que te diga. Don't do what he tells you.
Iré a donde V. me diga. I shall go wherever you tell me.

c. After a superlative or a word of similar character (but only in the present perfect tense).

Es el mejor hombre que
jamás haya
(or he) visto.
He is the best man I have ever seen.
Es el maestro más inteligente que jamás haya (or ha)
venido a esta escuela.
He is the most intelligent teacher that has ever come to this school.

327. When the relative clause expresses certainty or definiteness with respect to the antecedent the indicative is used.

Tenía un hijo que le mantenía. He had a son who supported him.
Busco al criado que ví ayer. I am looking for the servant I
saw yesterday.

328. Learn the conjugation of the verbs andar (472), caber (473), and oír (482) in the tenses of the indicative and subjunctive.