explain how stem-changing –ir verbs are different from stem-changing –ar and –er verbs in the present subjunctive.
In the present subjunctive, stem-changing -ir verbs are similar to stem-changing -ar and -er verbs in that they undergo a change in the stem in certain forms. However, the specific pattern of stem-changing for -ir verbs is different from that of -ar and -er verbs.
For stem-changing -ir verbs in the present subjunctive, the stem change typically occurs in the third person singular (él/ella/usted) and the third person plural (ellos/ellas/ustedes) forms. The stem change in -ir verbs generally involves a change of e to ie or o to ue.
For example, in the verb "dormir" (to sleep), the stem change occurs in the third person singular form "duerma" and the third person plural form "duerman." In the verb "sentir" (to feel), the stem change occurs in the third person singular form "sienta" and the third person plural form "sientan."
On the other hand, for stem-changing -ar and -er verbs in the present subjunctive, the stem change typically occurs in the second person singular (tú) and the third person singular (él/ella/usted) forms. The stem change in -ar and -er verbs generally involves a change of e to ie or o to ue, similar to -ir verbs.
Overall, stem-changing -ir verbs in the present subjunctive are different from stem-changing -ar and -er verbs in terms of when and how the stem change occurs. However, the concept of stem-changing verbs in the present subjunctive is consistent across all three verb types.