题目内容：
Speaker A : Could you give me a ride to the conference center? My presentation is in about half an hour.Speaker B：__________Have you checked with Bob? He seems to be on his way there about this time. A．I'm sorry. Perhaps next time.
B．I'm glad to. But it's too late.
C．I'm afraid I am going to the opposite direction.
D．Excuse me, but I'm going to the conference center.
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