40．-- How much do I owe you for lunch?

　　　 -- ________ ．It’s nothing．

　　　 A．Come on　　 　　 B．Go ahead　　 　　 C．With pleasure　 D．Forget it

39．It was not until she got to the classroom ________ Lily realized she had left her textbook in the dormitory．

　　　 A．that　　　 　　　　　 B．where　 　　　　　　 C．when　　 　　　　　 D．before