Never before such a wonderful park, I'd like to pay a visit again.
A. had I seen; where
B. have I seen; which
C. have I seen; where
D. had I seen; which
网友回答
A. had I seen; where
B. have I seen; which
(答案→)C. have I seen; where
D. had I seen; which
解析：考查倒装和定语从句。否定词never, seldom,hardly等位于句首时，句子使用部分倒装，即把do/does/did/will/have等提到主语之前，过去完成时指“过去的过去”，这里没有明显的过去的动作，排除A、D；根据第二空前面的逗号可知，是非限制性定语从句，I'd like to pay a visit again主谓宾完整，不缺少成分，排除which，park是地点，故用where，故选C。