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.when
B.while
C.then
D.as
答案:A
解析:
解析:
|
导解:when表示“就在这时,这时突然”,与主句的完成时呼应. |
练习册系列答案
相关题目