Las Perífrasis Verbales con gerundio are the combination of two verbs in which the first verb is the one that is conjugated in any tense and any form or person and the second verb stays in the gerund form. There's no preposition linking both verbs.
Here is a list of a few common períffrasis verbales followed by a gerund and its uses:
Here is a list of a few common períffrasis verbales followed by a gerund and its uses: