题目内容：

The students were walking through the door,two at ________ time
A.a B.an C.the D./
请说明理由,还有这句话的意思

优质解答

选a,at time是不对的搭配,只有“at times”-有时；at the time是“那时”的意思；at a time是“每次、一次”的意思.
“学生们正在通过大门,每次只能过2位”