ITU-TG692建议DWDM系统的频率问隔为（）的整数倍。
A.155Mfz
B.100GHz
C.1OTHz
D.200GHz
参考答案：B
Which is more useful, English or Chinese?
A. each of B. none of C. both of
粪便中的脓细胞来自淋巴细胞。()
