1) The document discusses the simple past tense and simple present tense in English grammar.
2) For the simple past tense, regular verbs are formed by adding "-ed" and irregular verbs have their own past forms. The simple past tense is used to talk about completed actions in the past.
3) For the simple present tense, regular verbs are formed by adding "-s" for third person singular subjects and "-es" for verbs ending in certain letters. The simple present tense expresses general truths, habitual actions, and things that happen often or regularly.