[color=blue]Quickly he ran down the hill. It was very dark here, and he could not see very well.
Why could he not see very well?
He could not see very well because it was very dark.
I think the ‘it’ in the answer is the ‘dummy subject’ because I have a form of ‘be’ and an adjective. On the other side, the answer expresses an opinion about the place, doesn’t it?
Am I right in my assumptions?
Thanks in advance.