下图书中记载的科技成就是( )
A:造纸术
B:活字印刷术
C:造船技术
D:指南针
A. I love you, Mum.
B. What colour is it?
C. My favourite colour is green.
D. Thank you to my teachers!
E. What's your favourite song?
下列历代措施中,不能起到加强中央集权作用的有