PRESENT PERFECT TENSE
Present Perfect expresses the completion of an action by the time of speaking or writing.
• The holidays are over. Schools have reopened.
• I have written a book on English Grammar.
Present Perfect is used to refer to an activity or experience which has occurred in the past:
• Mr Banerji has been to England.
• Have you ever seen a rainbow?
The present perfect in English does not (generally) take an adverb of past time, Viz: last week, yesterday, last month.
We don’t say:
• Joyati has finished her work last week.
• They have got back from Nepal yesterday.
Instead simple past is chosen when an adverb of past time is mentioned.
• I saw Kulkarni yesterday.
• We found a treasure last week.
However, present perfect is used with adverbs/ prepositional phrases of time like these: so far, up till now, since, just, yet, already
• I have not written to mother since January.
Present perfect tense can be used with adverbs of frequency.
• Have you ever seen a zebra?
• I have always paid attention to music lessons.
Present perfect like simple present is used in an adverb clause of time when the main clause is in future time:
• I will get off when the bus stops / has stopped.
• They shan’t go home until they finish/have finished the job.
PRESENT PREFECT PROGRESSIVE
The present perfect progressive indicates an action began in the past and still going on, i.e. continuing upto the time of speaking or writing:
• The baby has been crying.
• What have you been doing?
It can be used with time phrase like theses: for, since, all the time, all day, and all week
• Lata has been talking all the time.
• We have been playing chess all the time.
SIMPLE PAST
Simple past is used for a past action when the time of an action is mentioned. In such a sentence an adverb of time is often used.
• Mrs Rao left this place a month ago.
• The screening of the film started at 7 p.m.
Simple past is also used in conditional sentences to indicate an improbable condition:
• If a ghost appeared we would scream.
• I wish I knew typing
PAST PERFECT
Past Perfect is used to report complete actions or events that happened before another point in past.
• The chief guest arrived at 5 P.M. Our team had scored two goals already.
• Malini was twenty-five. She had published a novel then.
Past Perfect is used to indicate that one action had been completed before another started. Past Perfect is used with the earlier action and Simple past with the later action:
• The bus left at 7 p.m. We got to the bus station at 7.15 p.m.
• The bus had left when we got to the bus station.
Past Perfect is used in conditional clauses to indicate non-fulfilment of a condition in the past:
• If he had gone to Agra he would have seen the Taj Mahal
• Had his flight been on time, he would have seen the Taj Mahal.
Past Perfect + infinitive express an unfulfilled hope/intention etc.:
• I had hoped to win a lottery.