将矩形纸片ABCD按如图所示的方式折叠,得到菱形AECF.若AB=3,则BC的长为( )
2014月5日,甲午年清明公祭轩辕黄帝典礼在陕西省黄陵县黄帝陵揭幕,来自全国各地及海外华人华侨近万人参加典礼。下列有关黄帝的叙述不正确的是( )
When you see an English film or talk with native speakers, observe their facial expressions and g____.