If I say:
It could be interesting
= "the thing had a chance to be interesting" — either was or wasn't interesting.
It could have been interesting
= "the thing could be interesting, but actually it wasn't."
And what about:
You could do it
= "I don't understand why you didn't do it."
"You could have done it"
= I don't understand why you didn't do it.
Which one is correct?
Best Answer
"It could be interesting" is an expression about a future event, not a past event. "Could be" is not the past tense of can. Could is a helping verb that indicates possibility and modifies "be", which is simple present tense. The past tense of this, as you know, is "could have been".
This works the same with other verbs:
Other examples: