在PON系统中,如果要传输CATV信号,采用的波长是()。
A. 1310nm
B. 1490nm
C. 1550nm
D. 850nm
淋病的实验室确诊试验是()艾滋病的实验室确诊试验是()
A. 蛋白印迹法
B. ELISA
C. VDRL
D. 细菌培养
E. TRUST
It()aroundsixo’clockwhenIdrovebackyesterdaybecauseitwasalreadydark.
A. must have been
B. must he
C. was to be
D. had to be