—Sure!The actor _______ a hero used to be a schoolteacher.I like him very much.
A:who play
B:which plays
C:who plays
D:that play
今年山东省关停70家产能落后的企业。这种做法正确吗,为什么?
如图,正方形A1A2B1C1,A2A3B2C2,…Anan+1BnCn,如图位置依次摆放,已知点C1,C2,C3…,Cn在直线y=x上,点A1的坐标为(1,0).
(1)写出正方形A1A2B1C1,A2A3B2C2,…Anan+1BnCn,的位似中心坐标;
(2)正方形A4A3B4C4四个顶点的坐标.
FeCl3溶液和Fe(OH)3胶体共同具备的特性是( )