单项选择题
M: Are these shoes on sale, too W: No, they aren’t. They are selling at the regular price of fifty dollars.
A.Yes, at the lower price. B.Yes, but not at a lower price. C.No, they are not for sale.
A.Operator and caller. B.Librarian and student. C.Customer and repairman.
A./... / B.The... the C.The... a D.The... /