仲裁庭对当事人之间的争议案件经过审理，双方当事人如果不能调解，应当作出裁决书。关于裁决书，下列哪些说法是正确的？

A.当事人协议不愿写明争议事实和裁决理由的，可以不写

B.裁决书由仲裁员签名，加盖仲裁委员会印章

C.对裁决持不同意见的仲裁员，可以签名，也可以不签名

D.对裁决持不同意见的仲裁员，必须签名

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．NAT

B．NCP

C．DDN

D．DNS