【单选题】听力原文: The most important message that humans deliver to one another often comes in just three words. Think of 'I love you' or 'There's no charge'. One of the phrases that I found most useful is this, ...
A.
They can be used to do business with people.
B.
They can be used to express all kinds of feelings.
C.
They can be used to deliver all the messages in our life.
D.
They can be used to convey our most important messages to people.