【题目】He asked them to come to his office one ________.
A.at no timeB.at one timeC.at a timeD.in no time
在线课程【答案】C
【解析】
考查介词短语辨析。句意：他要求他们一次一个到他的办公室。A. at no time从不；B. at one time曾经；C. at a time一次；D. in no time立刻。结合句意可知，此处用“一次”符合语境，one at a time“一次一个”，故选C项。