Students have roles, one being the person asking "Could you" and the other being the person doing the service. I included the library roles as they appear in the test and can help students be more prepared.
Hand out the cards and have the students pair up with the correct counterpart. The dialogue should look like this:
"Could I borrow this book?"
"No problem. Show me your card."
"Could you make me one?"
"All right."
*This example is straight from the test (Except the test has "I don't have one. Could you make me one?")
It may even be better to have the first line of conversation be "May I ask you a favor" and then continue into the dialogue request.
Have students switch roles so they can read the parts from both sides.
You can also have students switch cards with others so that they can complete different situations.
Google Docs Link: https://docs.google.com/document/d/1yfL5EkK-1rHPTK4z4Dx2hWXwHAKvkzwwee1jNlxiH5M/edit?usp=sharing