Atmospheres laden with coal dust or grain dust caused by loading these cargoes（）.

A.require loading operations to be shut down until the atmosphere clears

B.are toxic to human life

C.are subject to spontaneous combustion

D.may be explosive in some concentrations

数据库系统的主要特点为数据集成性、数据的高______和低冗余性、数据独立性和数据统一管理和控制。