A:①④
B:②③
C:①②③
D:①②③④
设正项等比数列an,lgan成等差数列,公差d=lg3,且lgan的前三项和为6lg3,则an的通项为( )
根据图表信息,补全对话
1. Q: When is Gina Brown's birthday?
A: ____
2. Q: ____
A: She is 12 years old.
3. Q: Is David Green's birthday on July 12th?
4. Q: ____
A: His birthday is on October 22nd.
5. Q: What's his age?
A: ____
已知A、B、C是单位圆上三个互不相同的点.若AB→=AC→,则AB→·AC→的最小值是( )
下列四个几何体中,主视图、左视图与俯视图是全等形的几何体是()