1) "See you later" is an appropriate
greeting for everybody.
2) "Bye" is a standard goodbye.
3) "Bye-Bye!" is a normal way that most people say goodbye.
4) "What's up?" is a formal way of greeting somebody.
5) "Hey" is a casual way to greet anybody.
6) "How are you doing" is a formal OR casual way to greet somebody.
7) You should say hello to your grandma by saying: "Hey, man."
8) "Hello, how are you?" is a great way to say hi to your teacher.
9) "See you soon" is a formal or informal way of saying goodbye to
somebody.
10) Saying "Bye!" is a formal and informal way of saying goodbye.