情境因素。
参考答案：
是指消费或购买活动发生时个体所面临的短暂的环境因素，如购物时的气候、购物场所的拥挤程度、消费者的心情等。
Frame Relay is simplified form of (25) , similar in principle to (26) , in which synchronous, frames of data are routed to different destinations depending on header information . Packets are routed throught one or more Virtual Circuits known as (27) . Most Virtual Circuits are (28) ,which means that the network provider sets up all DLCI connections at subscription time. (29) are also part of the Frame Relay specification . They privide a link that only lasts only as long as the session.
29（）
A．Permanent Circuits
B．Permanent Virtual Circuits
C．Switched Virtual Circuits
D．Switched Circuits
A319-112/115飞机上的发报机使用时间是（）.
A.24小时
B.36小时
C.48小时
D.72小时
