题目

The Spanish sculptor Isaac Cordal sees the city as his playground.He specializes in miniature，a street art often representing a social commentary as a critical observation on capitalism，power and so on.Cordal first models the sculptures in clay then reproduces them in cement(水泥)about 15cm in height.“As a material，cement seems very symbolic because it is one of our most recognizable footprints against nature.”he says.“Today we have been too used to cement city habitat.”For several years he’s been working on the project，Cement Eclipses，referring to the state when a buildi已知方程x2-2ix+b=1有实根，则实数b满足A.b=0B.b=1C.b＜0D.b≤0