He asked them to come to his office one . A. at a timeB. at all timeC. at timesD. at one t

问题补充：

He asked them to come to his office one .

A. at a time

B. at all time

C. at times

D. at one time

答案：

(答案→)A. at a time

B. at all time

C. at times

D. at one time

解析：考查词组：A. at a time一次B. at all time一直C. at times有时D. at one time曾经，句意：他叫他们一次一个去他的办公室。选A。