Mary, come here. I've found the book our teacher recommended us to buy last week.
Really? How much is it? Oh, it's 42 yuan! How expensive!
You know, it is the best seller for this year. It has had its fifth impression since its publication early this year.
How come? I have never seen such a popular book before.
Wait a minute. I found there were two printings. The paperback books must be much cheaper.
You are right. Let's buy the cheaper one.