shun Tang wrote:

>
> Ex:1 He has worked in that company IN THE PAST.
> Ex:2 Frequency graph shows how often each number has hit IN THE PAST YEAR.
> Ex:3 There have been great improvements in school teaching IN THE PAST TEN
> YEARS.
> Ex:4 As a result, the number of multiple births in the U.S. has more than
> quadrupled DURING THE PAST QUARTER-CENTURY.
> Ex:5 At least IN THE PAST FEW YEARS exitways from central Paris have been
> greatly improved.
> Ex:6 This function has greatly increased in importance OVER THE PAST HUNDRED
> YEARS.
>  My examples show that we still use Present
> Perfect even we have past time adverbials mentioned.
>

An easy rule of thumb:
If there is a possibility of repetition, I would use the present perfect.

Ex:1 He has worked for/in that company IN THE PAST.

The unwritten extension of the sentence, for me, is

" and there is a possibility that he might/ could/ will work for them again."
e.g.
Ex2 The frequency chart will show that this year, too!
Ex3 ANd improvements will continue ...hopefully :-)
Ex4 and multiple births could very likely increase even more.
Ex5 and will continue to be improved
Ex6 and will probably increase even more.

The use of Past Simple is possible but would imply ( simply) any further progress
was stopped or no longer possible for some reason.
I know we can start to complicate this but it functions for the majority of
purposes.

Greetings from Germany

Patsi
(originally from UK)

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