Which two statements are true about the roles in the Oracle database？（） ["A role can be granted to itself.","Roles are owned by the SYS user.","Roles can be granted to other roles.","A role cannot be assigned external authentication.","A role can contain both system and object privileges."]
新规程有关施工质量评定工作的组织要求中大型工程人数宜不少于（）人。 ["5","7","10","15"]
冻结存款的期限为（）。 ["三个月","六个月","九个月","十二个月"]
赵先生，45岁。患“冠心病”18年，住院期间突然神志丧失，呼吸不规则，即刻进行心肺复苏。判断心脏按压是否有效的标志是（） ["测血压","呼喊患者看其是否清醒","触及挠动脉搏动","触及颈动脉搏动","胸部起伏"]
水泥的3日和28日的抗压强度和抗折强度是采用（）测定的。 ["胶砂法","坍落度","干燥器法","穿孔法"]
简述校园文化的积极功能。
