Which two of these are correct regarding the recommended practice for distribution layer design based on the following configuration?（） [" use a Layer 2 link between distribution switches"," use a Layer 3 link between distribution switches"," use a redundant link to the core"," use a Layer 3 link between distribution switches with route summarizatio"]
电力管理部门应将经批准的电力设施新建、改建或扩建的规划和计划通知（），并划定保护区域。 ["安全部门","劳动部门","城乡建设规划主管部门","施工部门"]
压力表如果仅是最后一点示值小，多是因为连杆与扇齿的夹角（） ["过大","过小","没有关系","无法确定"]
自然行为的偶然观察是一种有计划的非连续偶然观察。
建设长江上游生态屏障，四川实施的主要工程有（）。 ["天然林保护","生态环境综合整治","退耕还林还草","碧水蓝天","水土保持"]
简述现代碳酸盐沉积环境。
