Unit 5: The infinitive, stem-change verbs, and por and para
5.2 Stem-Changing Verbs
There are many -ar, -er and -ir stem-changing (sometimes called “radical” [“having to do with the root”]) verbs in Spanish.
In the most common patterns, the e of the stem changes to ie, the o to ue, and the e to i. All of these changes occur only in stressed syllables, in other words, in all persons except nosotros and vosotros. That the stems of these verbs change should not present comprehension problems, provided that you recognize the infinitives.
| pensar (to think) | dormir (to sleep) | pedir (to ask for/request) | |
|---|---|---|---|
| yo | pienso | duermo | pido |
| tú | piensas | duermes | pides |
| él, ella, Ud. | piensa | duerme | pide |
| nosotros | pensamos | dormimos | pedimos |
| vosotros | pensáis | dormís | pedís |
| ellos, ellas, Uds. | piensan | duermen | piden |
One exception to the above pattern is the verb jugar (“to play” [a sport, a game]), which used to have an o in the stem, but made a late shift to a u, which is the vowel that changes to ue.
In the vocabulary lists in this text, stem-changing verbs are indicated by the vowel(s) to which the stem changes, put in parentheses immediately after the infinitive. Ex. dormir (ue)
