南北半球的分界线是( )
A:回归线
B:赤道
C:极圈
D:本初子午线
印度的地形分布特点是( )
Sam has got a bike. He goes to school by bike. Amy hasn't got a bike. Her father has got a car. She goes to school in her father's car. Daming hasn't got a bike. He goes to school by bus.
等腰三角形一腰上的中线把周长分为15cm和27cm的两部分,则这个等腰三角形的底边长是( )