Irregular 'IR' Verbs: Radical Changing Stems
Spanish: Cambridge International GCSE, topic 10.6.14
Radically Changing IR Verbs (O → UE, (E → IE), (E → I)
Verbs that have radical changing stems in the present tense are also radically changing in the present subjunctive. In the 'nosotros' and 'vosotros' forms these verbs drop the ‘e’. Here are a couple of examples:

Dormir
- Duerma - I sleep.
- Duermas - you sleep.
- Duerma - he/she sleeps / you sleep (formal).
- Durmamos - we sleep.
- Durmáis - you sleep (plural).
- Duerman - they sleep / you sleep (formal plural).

Sentir
- Sienta - I feel.
- Sientas - you feel.
- Sienta - he/she feels / you feel (formal).
- Sintamos - we feel.
- Sintáis - you feel (plural).
- Sientan - they feel / you feel (formal plural).

Pedir
- Pida - I ask.
- Pidas - you ask.
- Pida - he/she asks / you ask (formal).
- Pidamos - we ask.
- Pidáis - you ask (plural).
- Pidan - they ask / you ask (formal plural).
Test yourself on Irregular 'IR' Verbs: Radical Changing Stems
How do you say 'we ask' in the present subjunctive in Spanish?