题目内容
I had been puzzled over the problem for over an hour without any result, ____ all at once the solution flashed across my mind.
A. while B. when C. then D. as
【答案】
B
【解析】
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题目内容
I had been puzzled over the problem for over an hour without any result, ____ all at once the solution flashed across my mind.
A. while B. when C. then D. as
B
【解析】