The highlighted part of the sentence is called a/an Professor Plum , who had been to the mansion before , expertly navigated the maze of rooms andcorridors to quickly reach the conservatory
I think this is what you are wanting to know. You would use a not an If the word/name (Professor Plum) would have been something starting with a vowel instead, you would use an
Is this what you were asking?
Answer:
freedom fighters fought for the freedom of our country. because of them we are celebrating Independence Day
They mostly wrote about Individual experiences.
hope this helps!
