A:细胞增殖
B:细胞全能性
C:细胞衰老
D:细胞癌变
—Did you know China is one of the oldest countries in the world?
—Yes, I did. It’s ______ than the US.
将如图所示的两个平面图形绕轴旋转一周,对其所得的立体图形,下列说法正确的是( )