... surveying function and confirming, declaratives for notifying, reasoning and advertising, reminding a good experience in Interrogatives. Both Vietnamese and British people, searching information ... Suggesting. It means that using PIs is necessary in communication. PIs in English and Vietnamese can have a variety of functions such as Surveying, Notifying, Reasoning, Confirming, Persuading, Advertising, ... Functionally, Pre -invitation sequences have many different functions in English and Vietnamese such as Surveying, Notifying, Reasoning, Confirming, Persuading, Advertising, Introducing, Showing...