The imperfect tense of -er and -ir verbs
The imperfect tense of -er and -ir verbs is formed using a different set of endings to -ar verbs. Almost all verbs commonly classed as "irregular" ending in -er/-ir also follow this pattern.
The basic pattern is that the infinitive ending (-er or -ir) is replaced with -ía. Then, regular person endings are added where necessary. Adding -ía then the person endings, this gives the following endings for the imperfect of -er and -ir verbs:
Next: practise these forms
On the next page, you can practise the above forms with an on-line imperfect tense exercise on -er and -ir verbs.