A、He forgot to assign homework to his students. B、He has no time to give the class. C、He is ill, but he has a class today. D、He

M: Math Department, Jimmy Brown speaking.
W: Hello, Professor Brown, this is Alice Hill calling, I’m a friend of your teaching assistant, David Williams. He’s got a bad cold. David asked me to call you because he’s lost his voice.
M: Lost his voice. Oh, poor boy! Is there anything I can do for him?
W: Well, he has a class this morning from ten to eleven thirty and he won’t he able to teach it, but he doesn’t want to cancel it either.
M: He wants me to try to find someone else to teach the class?
W: No, not exactly. What he wants to do is to get someone to go in for him, just to pass back the mid-term exams. He’s already marked them and they are on the desk in his office. The whole thing wouldn’t take more than ten minutes.
M: His classes are ten, eh? At that time I was going to he on campus anyway; so I could do it for him. What room is his class in?
W: Cander Hall, Room 214. Will you need his office key to get the exams? He’s given it to me and I can bring it to you.
M: Actually, that won’t be necessary. We have a master key in the maths department. So I can get into his office.
W: Thank you very much, Professor Brown. David doesn’t have another class to teach until Thursday, and hopefully, he will be able to talk by then. He’ll call you as soon as he can. Oh, yes, I almost forgot. Could you put the next assignment on the board, too? It’s all the problems on page forty-five, and they are due at the next class.