How to use "realised" in a sentence

I thought it was a rock, but then I realised it was metal

Was it because Mrs Lewis's testimony appeared in the newspapers only after the inquest? When he read the report, he realised that she had seen him opposite Miller's Court

There stood Miss Fairlie, alone outside in the moonlight, looking exactly like the woman in white! I suddenly realised that the 'something missing' was this: my realisation of the disturbing similarity between the fugitive from the asylum and my student at Limmeridge House.

I realised that she was listening at the door a moment ago.

The copy had no record of Percival's father's marriage! I realised that the record in the original register must be a forgery, added in years afterwards