决策树是用来描述DFD中（）的。
A.数据存储
B.数据流
C.外部实体
D.处理逻辑
参考答案：D
She was clearly a customer at Scott' s, as she told the waiter that she would stick to her favorite．
A．casual
B．common
C．regular
D．ordinary
注射剂中加入硫代硫酸钠作为抗氧剂时，通入的气体应该是
A．O2
B．H2
C．CO2
D．空气
E．N2
