Expression of Greeting
Greeting is something that is said or done to show people that you are happy to meet or see them. It is also defined as a message that expresses good wishes to someone. When you meet someone, greet him/her properly.
Expression of Leave-Taking
Leave Taking is an act of going away and saying goodbye. It is also used when you want to end a conversation politely.
Expression of Gratitude
Gratitude is a feeling of appreciation ot thanks.
Expression of Apology
Apology is a statement saying that you are sorry about something; an expression of regret for having done or said something wrong; or an expression of regret for not being able to do something.