表示
He decided to devote all his time and effort _____ scientific investigation.
He decided to devote all his time and effort \_\_\_\__ scientific investigation.
数据库概念设计的E-R方法中,用属性描述实体的特征,在E-R图中用___表示属性。
数据库概念设计的E-R方法中,用属性描述实体的特征,在E-R图中用___表示属性。D