对治疗指数的阐述哪一条是正确的

A．数值越大越安全

B．数值越大越不安全

C．可用LD₅/ED₅表示

D．可用LD₅₀/ED₉₅表示

E．不可从动物试验获得

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

A．VLAN

B．LANE 

C．VPN

D．IPOA