—I wonder why Mr. Brown hasn’ t showed up at the meeting yet.
—I’ m not sure, but he ______ in a traffic jam driving here.

A．Strangers.
B．Colleagues.
C．Interviewer and interviewees.
D．Classmates.

A．I’m not in the office.
B．No, I am.
C．I have homework to do.
D．I’m a student.