I used to go mountain—climbing every summer .A. at a timeB. at one timeC. At timesD. At th

I used to go mountain—climbing every summer .
A. at a time
B. at one time
C. At times
D. At the same time

A. at a time(答案→)B. at one timeC. At timesD. At the same time解析：at a time 一次；at one time 曾经

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