PAST SIMPLE AND PRESENT PERFECT I last bought a CD three years ago.
In this sentence, I use the past simple to talk about a finished action in a finished
time. I could also say:
I bought a CD for the last time three years ago. or I can bring the time expression to the beginning of the sentence and say:
The last time I bought a CD was three years ago. Another way to express this idea is using an expression like ‘for three years’.
Remember that we use the past simple with expressions of finished time like
‘3 weeks ago’ or ‘last year’ and in general any time we say when an action took place
or ask a question with ‘when’. The present perfect is used with expressions
of unfinished time lke ‘today’, ‘for 3 weeks’ or ‘since Christmas’.
The present perfect is also used with indefinite times like
‘already’or yet, ‘recently’ and ‘ever or never’. I can rewrite the sentence using the present
perfect and say: I haven’t bought a CD for three years.
Another way to rewrite the sentence is using the conjunction ‘since’.
It’s three years since I last bought a CD. He got that car when he left college.
To talk about an action that started in the past but continues in the present, I can use
the present perfect continuous. So, I can rewrite this sentence:
He has been driving that car since he left college Remember that some verbs like ‘be’, ‘have’ and ‘know’ are not normally used in continuous
tenses. So using the verb ‘have’, I rewrite the sentence using present perfect simple: He has had that car since he left college.
She has never drunk vodka before. With the expression ‘the first time’, we use
the present perfect because it’s the first time ‘ever’.
This is the first time she has ever drunk vodka. You can also use this construction with the
superlative. I have never seen a funnier film than ‘The Life of Brian’. ‘The Life of Brian’ is the funniest film I have ever seen.