接头损耗指标:单模光纤的平均接头损耗应不大于()dB／个。

单项选择题Who does Mr. Nolan think should be responsible for Neil’s death? A、 Neil’s parents. B、 Neil’s classmates. C、 Mr. Keating. D、 Neil himself.

单项选择题电视、录像等是()常用的设备和材料。