He told me that he once met an alien from space. This alien didn’t need oxygen to live; it didn’t have a nose. That’s the hard story to believe. I’m not sure he was telling me truth. Maybe he isn’t so honest, after all.
The above paragraph is copied from one of the online grammar test excerices. Iam making some mistakes in the articles usage. e.g.
I used the article before hard story but in result it is 'a'. I think hard story is describe in the first two sentences and it is clearly understandable which story it is talking about.