May I ask what the logic is behind using present perfect/infinitive + present perfect in "present perfect + since + present perfect" sentences?
it has been a while since I have enjoyed a party this much.
It's been a long time since I have read an interesting book.
Why is it not present perfect + past simple? I understand the "it's been" part, since it's something that is still relevant or going on. But if I'm referring to a specific past event, why should present perfect even be considered?
2) Also, I've seen people replace infinitive forms with present perfects:
"You must be surprised to receive a letter from me" = "You must be surprised to have received a letter from me"
Is there such thing as an infinitive present perfect? How is this construction possible?
Please help me understand!