下图示意某流域开发的三个阶段（a）和三条流量变化曲线（b）。完成下列问题。

Valentine's Day(情人节) is on February 14th every year. On this day, people send valentines(情人卡)to their loved ones, Valentine's Day is a special time to tell how much you care about a person.
Many people send candy in hearted shaped("心"状的)boxes to people they love. Flowers are also presents that people send on Valentine's Day. Valentine cards with words are often used by many people.
Can you guess who gets the greatest number of Valentine cards in the United States each year? Is it mother or father, sister or brother? Is it uncle or aunt? Is it the special friend? No, it isn't!
Mothers get a lot of cards, but school teachers get the most each year. Do you know who sends the most? Children do. Children send five times as many on February 14th as adults do.

A: Look, Linda. What’s that?

B: It’s a coat. It’s a black one.  

A: ____ B: Yes, is it yours?

A: No. Mine is old. ____  

B: It looks like Mr. Smith’s.  

A: Look! He is there.  

B: ____  

A: Excuse me, Mr. Smith. ____  

C: Let me see. Yes, it is mine. Where do you get it?

B: ____

A: Here you are.  

C: Thank you very much.  

A: You are welcome.