Their first ____ had a white ____ on it. This is a symbol of good____.
造成野生动植物濒危和灭绝的主要原因是 ( )
设实数abc≠0,bca,cab,abc成等差数列,则下列不等式一定成立的是( )
一个圆的直径是10cm,另一个圆的面积比这个圆的面积少16πcm2,则另一个圆的半径长为 ____m.