描述信息系统逻辑模型的主要工具是( )。
A.业务流程图和数据流程图 B.组织机构图和业务流程图C.数据流程图和数据字典 D.系统流程图和数据字典
参考答案:C
髋关节置换手术选择硬膜外麻醉的优点有哪些?
Bats are surprisingly long-lived creatures, some ______ a life span of around 20 years.
A. having B. had C. have D. to have