Imperfect Subjunctive: Regular 'ER'
Spanish: Cambridge International GCSE, topic 10.7.3
Regular ER Verbs
The imperfect subjunctive stem is based on the 'ellos/ellas' form of the preterite tense. There are two sets of endings that are both widely used. It does not matter which endings you use. Here is the example of 'conocer':

The stem
- To form the stem you take the 'ellos/ellas' form of the preterite tense, ending in 'ieron'.
- You take off the 'ron' and add the endings.
- There are two sets of endings.

'Iera' endings
- Conociera - I knew.
- Conocieras - you knew.
- Conociera - he/she knew / you knew (formal).
- Conociéramos - we knew.
- Conocierais - you knew (plural).
- Conocieran - they knew / you knew (formal plural).

'Iese' endings
- Conociese - I knew.
- Conocieses - you knew.
- Conociese - he/she knew / you knew (formal).
- Conociésemos - we knew.
- Conocieseis - you knew (plural).
- Conociesen - they knew / you knew (formal plural).
Test yourself on Imperfect Subjunctive: Regular 'ER'
How do you say 'she ran' in the imperfect subjunctive?