The simple past tense is used to describe events that occurred in the past, whether recently or further in the past. There are two types of verbs in the simple past: regular verbs and irregular verbs. Regular verbs form the past tense by adding "-ed" to the base verb. Irregular verbs have variations in their past and past participle forms. Sentences in the simple past can be affirmative, interrogative, or negative. Interrogative and negative sentences use auxiliary "did" plus the base verb form.