单项选择题
A. none
B. one
C. two
D. three
E. four
单项选择题 The ONS 15216 is a 32-channel system. The ONS 15216 OADMs are capable of adding and dropping one， two， or four channels. How are the OADMs provisioned to add and drop specific channels？（）
多项选择题 Whatarethreerelevantdesignconsiderationswhenusingthe15216EDFA？（）
单项选择题 Ifthepoweris0dBm，whatisthepowerinmW？（）