Me ill give points and and friend.
what is a subject pronoun? explain what subject pronoun you might use to greet your doctor. what about your best friend? what’s the reason for this? how is this different from or similar to english?

A subject pronoun is what you call someone, for example you, him, and they. To greet your doctor you should use usted which means you but is only used formally in Spanish. To greet your best friend you would use tú because it also means you but it is informal and you would not talk to your best friend very formally. This is different from English because in English there is only one way to greet someone, ‘you’ while in Spanish there is an informal way ‘tú’ and formal way ‘usted’.

uhm what exactly is the question?