Cathy：Do you mind opening the door for me？Brown：__________A.Yes，I"ll do it．B.It’s

Cathy：Do you mind opening the door for me？Brown：__________

A.Yes，I"ll do it．

B.It’s nothin9．

C.That’s all right．

D.Not at all．

请帮忙给出正确答案和分析，谢谢！