圆锥的侧面展开图为扇形，若其弧长为2πcm，半径为2cm，则该圆锥的体积为___

社会主义民族问题的实质是( )

A．民族争端
B．人民内部矛盾
C．阶级斗争地反映
D．民族差异问题

_____made both her parents angry.

A．Betty comes home lately at night

B．Betty coming home late at night

C．Betty came home late at night

D．Betty’s coming home late at night

Extra lessons on Sundays put ______ pressure on students, who already have______ homework.[ ]

A. more; many  

B. many; number of

C. many; much of  

D. more; piles of

计划工作的起点是( )

A．确定目标

B．估量机会

C．确定可供选择的方案

D．确定前提条件

职业资格证书是劳动者持证上岗和用人单位录用员工的资格认证。