Passives | - | LearnEnglish
https://learnenglish.britishcouncil.org/.../passives06.01.2021 · The present perfect ( have changed) is used when we are talking about the present result of a past action or event. The present simple passive (are changed) tells us about the current situation. Normally, it does not necessarily mean that there is something different about the present as compared to the past.