Anita : Hello Ms. Ratu you looks so busy, may I help you?
Ms. Ratu : Yes I am. Could you please bring students' homework books in my table?
Anita : Sure, and where should I bring it to?
Ms Ratu : Please bring the books to your class, and say sorry to your friends that I may coming late to the class.
Anita : Okay Miss Ratu. Is there anything else?
Ms Ratu : No it's enough. Thank you very much for your help Anita.
Anita : You're welcome.
The sentence "may I help you?" is the expression of ....