组成染色体和染色质的重要物质是 ( )
A:DNA和蛋白质
B:DNA和RNA
C:DNA和糖类
D:RNA和蛋白质
—I hope that what we have said will not fall on deaf ears.
— Don’t worry. It’s good for their study. They will follow it.
已知抛物线y=﹣x2+1的顶点为P,点A是第一象限内该二次函数图象上一点,过点A作x轴的平行线交二次函数图象于点B,分别过点B、A作x轴的垂线,垂足分别为C、D,连结PA、PD,PD交AB于点E,△PAD与△PEA相似吗?( )