2007年实行自动许可是按一般商品、机电产品(包括旧机电产品)、重要工业品三个目录进行管理的，下列关于自动进口许可的说法正确的是（）。

TCP functions at the Open System Interconnection(OSI)(61)layer, or Layer 4. Its chief responsibility is to ensure(62)end-to-end connectivity. IP, located one layer down, at the OSI network layer, or Layer 3, communicates the addresses of each(63)sender and receiver to the routers along the way. Routers and Layer 3 switches can read IP and other Layer 3(64). This information, combined with routing tables and other network intelligence, is all it takes to get(65)the room or around the world via TCP/IP.

A．transpose

B．translate

C．transmit

D．transport

选出应填入下面一段英语中______内的正确答案。

TCP functions at the Open System Interconnection (OSl)(1)layer, or Layer 4. Its chief responsibility is to ensure(2)end-to-end connectivity. IP, located one layer down, at the OSI network layer, or Layer 3,communicates the addresses of each(3)sender and receiver to the routers along the way. Routers and Layer 3 switches can read IP and other Layer 3(4). This information, combined with routing tables and other network intelligence, is all it takes to get(5)the room or around the world via TCP/IP.

In the open systems interconnection (OSI) reference model, "layer" means one of seven conceptually complete,(71) arranged groups of services, functions, and protocols, that extend across all open systems.Application layer provides means for the application(72) to access the OSI environment. Presentation layer provides for the selection of a common syntax for representing data.(73) layer provides the means necessary for cooperating presentation entities to organize and synchronize their dialog and to manage their data exchange. Transport layer provides a reliable end-to-end data transfer service. Network layer provides for the entities in the transport layer the means for transferring blocks of data, by(74) and switching through the network between the open systems in which those entities reside. Data link layer provides services to transfer data between network layer entities. Physical layer provides the mechanical, electrical, functional, and procedural means to establish, maintain and(75) physical connections for transfer of bits over a transmission medium.

A．rankly

B．levelly

C．layered

D．hierarchically

A.Organization for Standards Institute

B.Organization for Internet Standards

C.Open Standards Institute

D.Open Systems Interconnection

A．A.Organization for Standards Institute

B．B.Organization for Internet Standards

C．C.Open Standards Institute

D．D.Open Systems Interconnection

A.Internal functions

B.External functions

C.Information systems

D.Physical distribution

A．错误

B．正确