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Grammar
Simple Past/Present Perfect
>>The Internet economy
has helped
unemployment rates reach record lows.
To make the present perfect, use:
subject + have/has + past participle
Some of the main uses of the present perfect are:
1. To express a completed action at an indefinite time in the past.
>>
I've been
to Mexico twice.
You know the speaker has been to Mexico, but you don't know when.
>>
Have
you
been
to Mexico?
>>I
haven't been
to Mexico, but
I've been
to Guatemala.
2. With
yet
,
still
,
already
,
ever
and
never
.
>>
Have
you
ever been
to Peru? No,
I've never been
to Peru.
>>I
haven't written
the letter
yet
.
I
still
haven't
written
the letter.
>>Could I have the report by Friday?
I've already done
it.
All these examples show that something has happened (or not happened) but you don't know exactly when.
3. With
for
and
since
, to express a situation that began in the past and continues to the present.
>>
I've been
in New York
for
three months.
This action started three months ago and continues into the present.
>>
Has he been
in New York for three months?
We use the simple past when we know exactly when an action happened.
>>I
went
to Bolivia
last year
.
>>
Did you see
Jan
yesterday
?
>>I
didn't go
to the Mardi Gras party on
Tuesday
.
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