Excuse me,what time _______ train ___________?--At 8:10 a.m.

題目：

Excuse me,what time _______ train ___________?--At 8:10 a.m.tomorrow morning.
A.does;pull out B.is ;about to pull out C.is;to pull out
選A,求分析

解答：

A..does;pull out
..