21. What does the author say about his customers?

A .They can not count numbers.

B. They sometimes jump the queue.

C. They don’t know how to express themselves.

D. They behave as if their memories had totally failed.

22. According to the text, who are supposed to be in the express line?

A  Customers with nothing purchased.

B.  Customers with not more than 15 items.

C. Customers with items between 15 and 25

23. When customers arrive at the check-out counter,they_______

A. find their pens lost               

B. go back and get more items

C. can not wait to pay for their groceries.