View the Exhibit to observe the roles assigned to the SL_REP user. Which statement is true about theassignment of the SELECT_CATALOG_ROLE role to the SL_REP user（）
A. The user must enable the role explicitly.
B. The user can grant the role to other users.
C. The user cannot use the role until the DBA enables it explicitly.
D. The user can start using the role immediately without any change
碳素工具钢都是优质或高级优质钢，其含碳量一般大于0、7％。
A. 正确
B. 错误
角色游戏中幼儿从独自游戏发展为平行游戏，主要反映了幼儿()
A. 认识发展水平
B. 社会性发展水平
C. 情感发展水平
D. 身体发展水平
泥石流的治理措施主要有：拦截措施、滞留措施、________措施。
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