①当前教育的中心工作是资助落后地区的贫困生
②实施科教兴国战略
③促进教育均衡发展,实现教育公平
④保障义务教育的健康发展
A:①②③
B:②③④
C:①②④
D:①③④
— Alice, could you help me ________ meat? I want to make some dumplings for dinner.
— OK. I'll do it right away.
AB为⊙O直径,BC为⊙O切线,切点为B,CO平行于弦AD,作直线DC.
①求证:DC为⊙O切线;
②若AD•OC=8,求⊙O半径r.
—Two windows.