—Can I call you back at two o’clock this afternoon?
—I’m sorry, but by then I to Beijing. How about five?
A. fly
B. will fly
C. will be flying
D. am flying
网友回答
A. fly
B. will fly
(答案→)C. will be flying
D. am flying
解析：考查动词时态。根据问句中的two o’clock和应答句中的by then可知所填词表示的动作在当时正在进行，用将来进行时，选C。