While correcting some finals, a question arose concerning possible answers to a “fill in the blank” question. The initial question asked students to fill in the blank with the proper tense of the verb in the parenthesis. The question read:

“You missed your plane. The flight _______ at 10 o’clock.” (leave)

While most of the students answered in the simple past (left), there were several that answered “leaves”.
To me both answers could be correct. (1) Am I off base?; and (2) To elicit “left” as the only correct answer, should the question have been worded “Your flight ______ at 10 0’clock”?