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English is my second language and I have always been confused with 'have been/has been' and the idea that it could be replaced with 'was' in some contexts.
For instance, this is a part of an urgent email about a bomb threat:
An unconfirmed bomb threat has been received. The halls are being evacuated. More info to follow.
My doubt is: why couldn't it be 'was received' and what that would change?
The thumbnails base has been updated.
Many times, I see 'have/has been' in something that could be 'was' from my understanding.
This is a question I have been asking myself for a long time.
I would appreciate if someone could help me.