—Why can your neighbor know so much about London?—He have been there before.A. mustB. can

问题补充：

—Why can your neighbor know so much about London?

—He have been there before.

A. must

B. can

C. should

D. need

答案：

(答案→)A. must

B. can

C. should

D. need

解析：考查情态动词用法。考查情态动词表示推测的用法。Must表示有把握的肯定推测。结合句意可知A正确。句意：他以前一定到过那里。