Final answer:
The verb 'was' in the sentence is in the preterit tense, indicating completed action in the past.
Step-by-step explanation:
The verb 'was' in the given sentence 'My team was the winning team last season' is in the past tense. Specifically, it is in the preterit tense. The preterit tense is used to describe completed actions in the past. In this sentence, it indicates that the team's status as the winning team lasted for a specific period of time in the past season.
Learn more about Verb tense in English