新装或大修后的变压器投运前,试验项目有工频耐压和()
A.变压器性能参数试验
B.绝缘电阻和吸收比测定
C.直流电阻测量
D.绝缘油试验
参考答案:A, B, C, D
— Where did you find Mr. Smith?
— It was in the library _____ we often went to read. [ ]
A. that
B. when
C. what
D. where
unipotent stem cell(单能干细胞)