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
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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