Learners with very limited language may simply refer to events in the order in which they occurred or mention a time or place to show that event occurred in the past.
e.g. My son come. He work in restaurant. He don’t like his boss.
Later, learners start to attach a grammatical morpheme which shows that the verb is marked for the past. After they begin marking past tense on verbs, learners may still make errors such as overgeneralization of the regular -ed ending.
e.g. John worked in the bank. He rided a bicycle