阅读下面的内容，完成下列各题。
Mrs Green's son works in a post office. Mrs Green wants to visit her son. But she doesn't know the way (路). So she asks an old man.
Mrs Green: Excuse me, sir. Where is the post office?
Old man: There are about forty post offices in the city. Which one do you want to go to?
(Mrs Green calls her son.)
Mrs Green: Dear son, where is your post office?
Mrs Green's son: It's on Renmin Street. It's next to a park.
Old man: Look! It's over there.
Mrs Green: Thanks very much.
Old man: You're welcome.