A series of attempts______made, he came to a successful solution of the problem.

游客2025-03-07 10

问题 A series of attempts______made, he came to a successful solution of the problem.

选项 A、to be
B、had been
C、were
D、having been

答案 D

解析这是一道语法题。考点是动词过去完成时被动语态的用法。

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