常规单模光纤的零色散波长窗口在()
A. 0.85µm
B. 1.31µm
C. 1.55µm
自由锻拔长圆形截面坯料时的变形特点是什么?易出现的质量问题、产生原因、常采取的预防措施是什么?
The theory of learning underlying the Grammar-Translation Method was Faculty Psychology. The Faculty Psychologists believed that the mind of human beings had various faculties which could be trained separately.()
A. 正确
B. 错误