制约光传输距离的两个主要因素是()和色散。
参考答案:衰减
______ number of the students in their school is about two thousand, ______ of them are boys.
A.A; two thirds
B.The; two third
C.The; two thirds
D.A; two third
肺结核患者的治疗效果是()
A.总治愈率为99%
B.新发肺结核的治愈率为95%以上
C.新发肺结核的治愈率为80%左右
D.新发肺结核的治愈率为85%以上
E.新发肺结核的治愈率为60%左右