架空管道分层布置时，乙炔管应该布置在（），其固定支架不应该固定在其他管道上。A.最上

受电弓日常维修，其目的时维持对架线的必要的压力。

For most of human history, the dominant concerns about energy have centered on the benefit side. Inadequacy of energy resources of the technologies for harvesting, converting, and distributing those resources has meant insufficient energy benefits to human beings and hence inconvenience, and constraints on its growth. The 1970’s, then, represented an turning point. Energy was seen to be getting costlier in all respects. It began to be believable that excessive energy costs could pose threats on a par with those of insufficient supply. It also became possible to think that expanding some forms of energy supply could create costs exceeding the benefits.

用于基金定期定额业务的借记卡处于司法冻结状态，系统将（）该业务。

关系数据模型有许多优点，但下面所列的条目中哪一条不是它的优点

A．结构简单

B．适用于集合操作

C．有标准语言

D．可表示复杂的语义

数据管理技术发展过程经过人工管理、文件系统和数据库系统3个阶段，其中数据独立性最高的阶段是 【1】 。