A:think , are
B:am thinking,are
C:thought, were
D:think, were
小红要过生日了,为了筹备生日聚会,准备自己动手用纸板制作一个底面半径为9cm,母线长为30cm的圆锥形生日礼帽,则这个圆锥形礼帽的侧面积为____cm2 。
“DNA指纹技术”在刑事侦破、亲子鉴定等方面作用巨大,主要根据DNA具有