TIME EXPRESSIONS WITH FOR OR SINCE
Three decades
FOR three decades
Have you seen Helen today?
ALL GOOD
Time unfinished
you / come here before?
Have you come here before?
RECENTLY
Yes, because it refers to the recent past
Over an hour
FOR over an hour
We have just bought a new car last week.
WROOOOOOOOOONG
We have just bought a new car
We do not use the present perfect with adverbials which refer to a finished past time
it / rain all day?
Has it rained all day?
TODAY
A few seconds
FOR a few seconds
We have bought a new car this week.
ALL GOOD
Time unfinished
who / we / forget to invite?
Who have we forgotten to invite?
JUST
Yes, it refers to the recent past
The beginning of the month
SINCE
When we were children we have been to California.
WROOOOOOOOOONG
We do not use the present perfect with adverbials which refer to a finished past time
we / not / hear that song already
We haven't heard that song already
Now that I am an adult
Yes, I'm still an adult.
The start
SINCE the start
I have seen that film yesterday.
WRONG!!!
I have seen that film
I saw that film
I / know him for three months
I have known him for three months.
LAST WEEK
No, time finished