A.Error

B.True

A.Complete hierarchy of standard mathematical signals, providing simultaneous digital transmission multiplexing and cross-connectivity

B.A hierarchy of standardized digital signals that can be cross-connected asynchronously

C.hierarchy that can be used for asynchronous digital transfers

D.A hierarchy of standardized digital signals that can be asynchronously reused

A.The nonlinear effect of the B.1550 nm-wavelength region is small.

B.The 1550nm wavelength region is suitable for long-distance transmission.

C.The EDFA operating wavelength flatness region is contained in this window.

D.None of the above