For/In the past/last twenty years, ...

[sitifan]

1. For the past twenty years, my father has worked in a school library. (the CAP exam, 2020)
2. In the past twenty years, my father has worked in a school library.
3. For the last twenty years, my father has worked in a school library.
4. In the last twenty years, my father has worked in a school library.
Are the above sentences all acceptable to native speakers?

 

[tedmc]

I think the present perfect tense (has worked) only goes with the preposition,"for" ( a period of time).

 

[5jj]

1. For the past twenty years, my father has worked in a school library.
2. In the past twenty years, my father has worked in a school library.
3. For the last twenty years, my father has worked in a school library.
4. In the last twenty years, my father has worked in a school library.

In #1 and #3, the father began working in a school library twenty years ago, and is still working in one.

in #2 and #4, we don't know the duration of the working in the library. We know only that ar some time(s) in the twenty years leading up to the time of utterance, the father has worked in a school library.

 

[sitifan]

In the past/last twenty years, my father worked in a school library.

For #2 and #4, is the past tense also correct in American English?

 

[sitifan]

Which does "over the past/last twenty yeasrs" mean, "for the past/last twenty yeasrs" or "in the past/last twenty yeasrs"?

 

[5jj]

'Over' expresses a similar idea to 'during'.

If something happens over a particular period of time or over something such as a meal, it happens during that time or during the meal.

The number of attacks on the capital had gone down over the past week.
Many strikes over the last few years have not ended successfully.

https://www.collinsdictionary.com/dictionary/english/over

 

[probus]

For #2 and #4, is the past tense also correct in American English?

Yes, and it's more likely than "has worked". In 2 and 4 it's difficult to think of a context in which we'd use "has worked".

 

[teechar]

I think the present perfect tense (has worked) only goes with the preposition,"for" ( a period of time).

What do you mean by that?

 

[Tdol]

I think the present perfect tense (has worked) only goes with the preposition,"for" ( a period of time).

Not in these cases in BrE.