Lana: Will you do me a favor?
Ben: It depends. What do you want me to do?
Lana: Could you take mom to the doctor?
She hurt her leg and she can't drive.
Ben: Why don't you take her?
Lana: Because I have to ask my boss for permission, and you don't have classes this week.
Ben: When?
Lana: Her appointment is for tomorrow afternoon at five, but you should leave early because of the traffic.
Ben: Tomorrow, at five? i can't. I arranged to meet my friends at five.
Lana: You can never do anything to help.