please come in one( ),not all together.A at a timeB at times C in a time D on a

题目

please come in one( ),not all together.A at a timeB at times C in a time D on a

答案

选A at a time每次 一次 请每次进来一个人 不要一起都进来
B at times有时
C in a time 一段时间后 不就
D on a time 一段时间