下列对于外币交易“一项交易观点”的表述不正确的是（）。

A.把购销业务及其以后的账款结算视为一项交易

B.汇率变动产生的外汇损益将在当期予以确认

C.对于购货业务，汇率变动产生的外汇损益调整购货成本

D.对于销售业务，汇率变动产生的外汇损益调整销售收入

______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．NAT 

B．NCP 

C．DDN

D．DNS