Present Perfect tense talks about indefinite past events. Sometimes, there is a difference in meaning: 1: The present perfect continuous can be used to emphasise the length of time that has passed. at the/this moment . perfect 1 Past simple / pr. The present perfect simple can be used (often with 'since' and 'for') to talk about unfinished actions that started in the past and are still true in the present. 4. once/twice a week/month etc. We CAN use the present perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc. 3. 2. 2. 5. They've waited for hours. TIME EXPRESSIONS . : to ask about the duration How long have you been in London? Pr. HOW LONG...? Past simple time expression past perfect; They had a party: after: the exams had finished. Tom is watching TV now. I have eaten pizza three times this week! We have seen this movie already. Perfect continuous tense is used to put emphasis on the duration of an action which has started in the past and continues up to the present, present perfect continuous is used a lot with time expressions such as for, since, all morning / all afternoon/ all evening/ all week / all day / all week / minutes. Unfinished time and states. Present perfect tense can be used with expressions that are unspecific in time: I have lost my purse. action in the past , but w e donÕ t specify the time. At present, now, at the moment – the present continuous tense. In 1989. esta tarde (a partir de las 5 más o menos) At the moment. Present Perfect Simple time expressions. When I was born. right/just now . Time expression past perfect past simple; After: the exams had finished, they had a party. He hasn’t done his homework all week. Allowed HTML tags: