answer:Here is a comprehensive chart (at the bottom of the page) of all of the English verb tenses. Perhaps a better example will be “I watched 22 movies yesterday” and “I have watched 22 movies in the past week.” These can both refer to the exact same thing. The first sentence is in past simple tense. This means that the action (watching 22 movies) occurred at a specific time in the past (yesterday). The second example is in present perfect tense. This means that all of the actions occurred at an unspecified point in the past, and the actions occurred within a range of time that starts in the past and leads up to the present. The term “perfect” means that the actions are complete. The range of time in this case starts one week ago and leads up to now. It is also important to point out that if I watched 23 movies in the past week, then “I have watched 22 movies…” is no longer considered true, I would have to say “I have watched 23 movies…”. The information must include all instances of the action in the time range, and the information must be current and up-to-date. “You forgot” (past simple) means that the person forgot something at a specific point in the past, but does not say anything about what has happened since that point in the past, such as remembering. “You have forgotten” means that the action occurred sometime in the past, but the time frame leads up to the present. This also means that the person did not remember in the period of time that leads up to the present.