Past tense upsetConjugation
or inflection of verbs is the collection of different forms of verbs. By changing their forms, often with suffixes and auxiliary words, they express the grammatical categories of verbs, such as person, number, tense, aspect, voice and mood. According to the conjugation form, verbs are divided into different verb classes, to which are assigned paradigms according to which the verbs of the class are conjugated.
More information for past tense upset can be found in the irregular verb database.