In(66)the strength of the carrier signal is varied to represent binary 1 or 0.(67)is a system that can map a name to an address and conversely an address to al name.(68)is a three-way handshaking authentication protocol that it's packets are encapsulated in the point-to-point protocol.(69)is an approach that enables an ATM switch to behave like a LAN switch.(70)is an guided media which is made of glass or plastic and transmits signals in the form. of light.

A．ASK

B．PSK

C．FSK

D．FDM