1. Present Subjunctive - Part 1
Forms
The present subjunctive is formed by adding the following endings to a verb stem. The regular forms of the present subjunctive are based on the verb stem of the yo form of the present indicative. Notice that, except in the yo form, the present subjunctive endings for -ar verbs are the same as the present indicative endings of -er verbs, and -er/-ir verbs in the subjunctive have the present indicative endings of -ar verbs.
-ar VERBS -er/-ir VERBS
-e -emos -a -amos
-es -éis -as -áis
-e -en -a -an

2. Present Subjunctive - Part 2
Compare the yo forms of the present indicative and the present subjunctive.
INDICATIVE SUBJUNCTIVE
pienso piense
leo lea
escribo escriba
tengo tenga
Irregular forms are presented in the Manual.
Functions
To indicate that the speaker doubts, disbelieves, or is uncertain about something. Here are some expressions that are normally followed by subjunctive forms.
Es dudoso que… Es (im)posible que…
Es (im)probable que… No es seguro que…

3. More on the Imperfect Forms Here is a review of imperfect forms.
-ar VERBS -er/-ir VERBS IRREGULAR
crear: mover: ser:
creaba movía era
creabas movías eras
creábamos movíamos éramos
creabais movíais erais
creaban movían eran
Functions
To express mental, emotional, or physical states in the past
To describe physical appearance in the past

4. Subjunctive in Adjectival Clauses
Functions
You are already familiar with the forms of the subjunctive. You must use the subjunctive to express a characteristic of a nonexistent or indefinite antecedent. The subjunctive appears in a clause that functions adjectivally, modifying the nonexistent or indefinite antecedent. The antecedent is indicated in bold in these examples.
No hay ningún argumento que There is no argument that will
me convenza. convince me.
The verb convencer is in the subjunctive because it describes a nonexistent argument.
No hay nadie que me pueda There is no one who can help me.
ayudar.
The verb poder is in the subjunctive because it describes a person who does not exist.
Cualquier cosa que necesiten… Whatever you (may) need…
The verb necesitar is in the subjunctive because it refers to an indefinite antecedent, cosa.