题目内容：
根据下面的文字资料回答题（ 1 ）In the strength of the carrier signal is varied to represent binary1 or 0．（ 2 ）is a system that can map a name to an address and conversely an addressto an name．
（ 3 ）is a three-way handshaking authentication protocol that it's packets areencapsulated inthe point-to-point protocol
（ 4 ）is an approach that enables an ATM Switch to behave like a LAN switch．
（ 5 ）is an guided media which is made of glass or plastic and trans mitssignals in the form of light．文中（ 1 ）处正确的答案是（ ）。 A．ASK
B．PSK
C．FSK
D．FDM
参考答案：
答案解析：