接入网的几种常用的接入方式有：（）、（）和（）。
参考答案：光纤接入；铜缆接入；无线接入
A _____ attack _____ in Pearl Harbor by the Japanese in 1941 led to the US entering the Second
World War. [ ]
A. surprising; was carried out
B. surprise; carried out
C. surprise; was carried out
D. surprised; carried out
因子A的自由度fA______。
A．fA=2
B．fA=3
C．fA=4
D．fA=5
