____My mum doesn't go to work on Sundays .
____She goes swimming on Sundays .
____I go to school on Mondays.
____Do you go to work on Mondays .
____Does Sam play football on Saturdays .
等差数列an的前m项和为30,前2m项和为100,则它的前3m项和是( )
用一个圆心角为90°半径为32cm的扇形作为一个圆锥的侧面(接缝处不重叠),则这个圆锥的底面圆的半径为____ cm.
下列关于名著的表述,不正确的一项是( )
人类在生物圈中扮演的角色是( )