A series of attempts（ ）made, he came to a successful solution to the problem.
A、
to be
B、
had been
C、
were
D、
having been
【正确答案】：D
【题目解析】：
根据后文came（谓语动词），中间没有连词，说明不能填谓语动词，不选BC。做尝试应该在解决问题之前，所以要用having done，选D。句意：经过一系列的尝试，他成功地解决了这个问题。
A series of attempts（ ）made, he came to a successful solution to the problem.
A series of attempts（ ）made, he came to a successful solution to the problem.
to be
had been
were
having been
根据后文came（谓语动词），中间没有连词，说明不能填谓语动词，不选BC。做尝试应该在解决问题之前，所以要用having done，选D。句意：经过一系列的尝试，他成功地解决了这个问题。