Good day everyone. So I have Michael Swan's grammar book "Practical English Usage" and there's a couple of sections concerning to usage of "could".
So in 82.3 it says that we use could to talk about general ability in the past and they give an example
It could be quite frightening if you were alone in our big old house.
As I understand this sentence, it's an open condition in the past and we can use when instead of if. But I don't quite understand why the authors of this book decided to give such an example in this section. Because there's another section 86 saing that we can use can, could, may and might to talk about typical behaviour and occurences. And they give this example:
In the days of sailing ships, a voyage round the world could take years.
Do the first and the second sentences have the same meaning like "something sometimes happened"?
I'd like to thank everyone beforehand who will find time to answer my question :)