"Libraries today are different from those in the 1800s. For example, the contents of libraries have changed greatly through the years."

I can't understand why it uses present perfect. I think with "Through the years" (in 1800s) it should use simple past. Thank you in advance:)

  • it should be "througout the years"
    – dockeryZ
    Commented Aug 24, 2016 at 1:32
  • They are both prep. So "through " is also right. Is it? Or not.. Plz excuse my poor English:(
    – Beth
    Commented Aug 24, 2016 at 4:38

1 Answer 1


The sentence is not about changes which happened in the 19th century but about changes which occurred in the years since the 19th century, as a result of which we have very different libraries today.

This is the core use of the present perfect: to mention a past eventuality ("contents changed") as the source from which a present state ("libraries today") arose.

For more about this see What is the perfect, and how should I use it?, especially §§ 3.1 Grammatical meaning, 3.2 Pragmatic meaning and 4. When and how should I use the perfect?.

  • I got it roughly. But how could we know the answer without guessing the meaning? I mean, Grammatically , using simple past is right or not? Thank you so much
    – Beth
    Commented Aug 24, 2016 at 4:46
  • @Beth It's grammatical, but it's a different focus. When you use the simple past, you are focused on the past; when you use the present perfect you are talking about the past in order to describe the present. Commented Aug 24, 2016 at 10:27

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .