Yeah, this can get tricky The operative words in your samples are "in the last" or "this" or "so far". They link or connect the action to the present.Originally Posted by shmshm
For example,
I've changed three jobs in the last couple of years. (up to now, starting two years ago)
In the last week or so I've heard a great many lies from him (up to now, starting a week ago)
This week I've been arrested two times on DUI charges (up to now, from the beginning of this week)
You cannot say:
I've changed three jobs last year (happened last year, now we have a new year, so it must be I changed three jobs last year)
Last week I've heard a great many lies from him (happened last week, now we have a new week, it must be last week I heard a great many lies from him)
A word to the wise:
Don't fall into the trap of mixing up
"last year" and "in the last year"
"last month" and "in the last month"
They are VERY different in meaning
"last year" simply means the year before now, and "in the last year" means from "now" all the way back to "now minus 365 days"
"last week" simply means the week before now, and "in the last week" means from "now" all the way back to "now minus 7 days"
See?
So, the bottom line is:
Present perfect:
1. so far
2. this week/month/year/century/millenium
3. In the last week/month/year/century/millenium
4. In the last couple of hours/weeks/months/years/centuries/milleniums
Past simple
1. Last week/month/year/century/millenium
2. A minute/month/year ago
I know I might have muddied things up a bit for you, maybe someone else can do a better job of explaining the fine points of the grammar of such sentences. I have little background in English grammar, I'm mostly a "fly by the seat of my pants" kind of guy