《序言》和《导言》中所阐发的观点属于什么？
参考答案：历史唯物主义。
The fifth generation computers, with artificial intelligence, _____ and perfected now.
A．developed
B．have developed
C．are being developed
D．will have been developed
岸台用FEC方式发送国内NAVTEX的专用频率为（）.
A、490
B、4209.5
C、518
D、A/B
