I stayed in Japan only a few matches, , I went through a series of hardship.
A. during when
B. at that time
C. during which time
D. of which time
网友回答
A. during when
B. at that time
(答案→)C. during which time
D. of which time
解析：考查定语从句。本题的先行词指的是比赛期间，which time指代先行词作为during的宾语。句意：—我在日本只待了几次比赛的时间，在此期间，我经历了一系列的困难。故C正确。