The other sentences have described the house but this one goes inside Harry’s head and tells us his thoughts.
He wondered when was the last time anyone had been inside Bathilda's house to check whether she was coping.
Going into Harry’s thoughts like this helps us feel closer to him, and safer.
Notice that there are no strong qualities used in this snippet. This makes Harry seem very calm, which is reassuring to us.
She wondered how long it had been since Salzman had last cleaned inside his apartment to make it fit for guests.
He wondered whether or not Admiral Lavinia had ever bargained with the specters to secure a safe passage.
I imagined how I might get the drunken man to move along without waking the scarecrow-like figure in the shadows.
To help you come up with a question, think of wh- words: who, what, when, how, where, why, whether—and also if!