The document summarizes irregular verb conjugations in the preterite tense in Spanish. It discusses how verbs ending in -car, -gar, and -zar undergo spelling changes in the yo form, changing c to qu, g to gu, and z to c, respectively. It also notes how stem-changing verbs ending in -ir can undergo stem changes in the third person singular and plural forms in the preterite. Examples are provided to illustrate the conjugations of common irregular verbs.