Imperative Irregular

Because the tú command for ser is the same as the present tense yo form of the verb saber, you must consider the context of the sentence in order to determine which of the two is intended. In the following examples, notice how using a subject pronoun clarifies these identical forms with completely different meanings.

• Sé tú médico porque así ganarás mucho dinero.
  Be a doctor because you will earn a lot of money. (affirmative tú command, ser)

• Yo sé que los médicos ganan mucho.
  I know that doctors earn a lot. (present tense yo form, saber)

If you tell someone whom you address as tú not to do something, it is a negative command and, thus, you must use a different form. Only the tú and the vosotros commands have different forms for the negative and the affirmative. For Ud. and Uds. commands, the same form is used for negative and affirmative commands.

Irregular affirmative tú commands

There are a few affirmative tú commands that are not like the present tense él form of the verb; these are considered irregular. The table below shows the the irregular affirmative tú commands for seven verbs.

Infinitive   Affirmative Tú Command    Translation 
 
tener        ten                       have 
 
poner        pon                       put
 
salir        sal                       leave
 
venir        ven                       come
 
hacer        haz                       make or do
 
decir        di                        say or tell
 
ser          sé                        be
 
ir           ve                        go

Modo Imperativo Verbos Irregulares