在ATM网络中，语音、数据、视频等都是以（）为单位进行传输和交换的。
参考答案：信元
Mother bought many tomatoes from the market two days ago, ____ some have gone bad due
to the bad weather. [ ]
A. of those
B. from which
C. of which
D. in which
有哪三种主要的图示法______。
A．AOA、PERT、CPM B．PERT、CPM、GERTC．前导、箭线、条件 D．AON、AOA、PDM
