INTERMEDIATE - GRAMMAR
What is the difference in meaning between:
has been observed in nature ...
first sentence suggests that it was observed in the past and we can
still observe it today.
present perfect tense links the past with today.
Usually something happened then and it is still happening today or
it still affects us today. It
is also used for the very recent past.
at these examples.
He made some tea.(past simple - he made it in the past, but we
don't know if he made it 5 minutes ago or several hours ago)
There have been a lot of strange stories.(present perfect - they
started in the past and are probably continuing now)
4a. She studied two languages at university.(past
simple - she may have done it recently or it may have been a long
time ago - we don't have enough information to know exactly)
I knew your parents for years.(past simple - suggests that I
used to know them, but I don't know them now.)