根据对话内容，用方框中所给的句子补全对话。选项中有一项是多余的。

(Mary and Nile are talking about the study after the period of online classes)

Mary: Hey, Nile. Long time no see. You look worried. What's the matter?

Nile:

Mary: Why do you think so?

Nile:

Mary: In fact, online classes are real challenges to us. What did you do then?

Nile:

Mary: I think you should improve your self-control ability.

Nile: I see.

Mary: Sounds great. Remember, the most important thing is to be a good time manager.

Nile:

A. I couldn't help playing computer games. B. OK, I will. Thank you. C. Because I didn't take the online classes carefully. D. Oh, I'm sorry to hear that. E. I'm afraid I can't go to the dream school, Mary. F. I'll be strict with myself.