单选题 —Did you look up the time of trains to Shanghai?
—Yes, the earliest train is ______ to leave at 5:30 am.

【正确答案】 D

【答案解析】[解析] be due to do意为“应该…/预期的”；be about to do不和时间状语连用；possible主语应为it；而likely与句意不合。