Your friend is describing people and places. Drag the correct articles based on how words sound (not how they're spelled!).
My professor is an honest person — she always tells the truth. She works at a university in London. Today the weather is perfect for a walk!
My professor is an honest person.
Use an before vowel sounds. "Honest" has a silent 'h', so it starts with the vowel sound /ɒ/. Sound beats spelling every time!
She works at a university in London.
Use a before consonant sounds. "University" starts with /juː/ — that's a consonant sound (like "you"), even though it's spelled with 'u'.
Today the weather is perfect for a walk!
Use the (definite article) when both speaker and listener know exactly what's being talked about. There's only one "weather" happening right now!