—Did you look up the time of trains to Shanghai?—Yes，the early train is to leave at 5：30

网友回答

A. likely
B. about
C. possible
(答案→)D. due
解析：考查固定句式。固定词组be likely to do sth可能做某事；be about to do sth马上就要做某事，与when连用；be due to do sth预定好了做某事；句意：—你有没有查一下去上海的火车时间表？—是的。最早的火车是在5点半就离开了。根据句意可知火车离开是事先预定好的事情，故D项正确。