Explanation:
To use a verb in the present progressive, you must first conjugate the verb estar to go with the subject. Then you use the present participle form of the main verb. The present participle in Spanish ends in – ando (for –ar verbs) or – iendo (for both – er and – ir verbs) and is the equivalent of an English verb ending in –ing. For example: Juan estudia (John studies) is the present tense. Juan está estudiando (John is studying) is the present progressive construction. You must have both parts in this contruction, or else it will not make sense.
An –ir verb that stem changes in the present tense will have an e>i or o>u stem in the present participle form. Here are some examples of –ir verbs:
infinitive present participle
dormir (to sleep) dormiendo (sleeping)
decir (to say/to tell) deciendo (saying/telling)
pedir (to request) pediendo (requesting)
**it's like adding -ing that the back to make it present and also if you notice, the r at the end are gone
All other verbs that stem change in the present tense will not have any stem change in the present participle form.
