Idon'tthinktheexperimentis

问题详情：

I don't think the experiment is ___ failure, because it has provided us with ___valuable experience for our future tests．

       A．不填; 不填        B．不填; a                C．a; a                   D．a; 不填

【回答】

D

知识点：冠词

题型：选择题