Question

1. what's different between past tense and present perfect tense ??
2. what's different "between" and "among" ??

Answer 1

1.  the different is :
past tense use for :
> Finished actions
> A finished action in someone's life 
> A finished action with no result in the present
> With a finished time word (last week, last month, yesterday)

present perfect tense use when :
> Unfinished actions that started in the past and continue to the present
> A finished action in someone's life (when the person is still alive: life experience)
> A finished action with a result in the present
> With an unfinished time word (this week, this month, today)

2. the different is :
>  between use for   separated two person, objec, or place
> among use for separated three or more than person, objec or place