Todo mundo sabe que preposições são complicadas, mas umas dicas sempre caem bem.
TALK and SPEAK TO, LISTEN TO, APOLOGIZE TO, EXPLAIN TO.
LOOK AT, STARE AT, LAUGH AT, POINT AT, SHOOT AT, AIM AT.
Mas, em alguns casos, é possivel usar tanto AT como TO. Por exemplo, em SHOUT ou THROW. Todavia, com sentidos diferentes.
SHOUT AT somebody (IF YOU ARE ANGRY)
The teacher shouted at the students so they stopped messing around the room.
SHOUT TO somebody (IF YOU WANT THEM TO HEAR YOU)
She had to shout to me because I was listening to loud music.
THROW something AT somebody / something (IF YOU WANT TO HIT SOMEONE)
Don’t throw pebbles at the window.
THROW something TO somebody (IF YOU WANT SOMEONE TO CATCH IT)
I threw the key to him so he could open the door.