我国中外合资有限公司的中方合营者可以是( )

A．国有企业

B．私营企业

C．合伙企业

D．自然人

E．国有独资公司

The network layer provides services to the transport layer. It can be based on either（71）. In both cases，its main job is （72） packets from the source to the destination. In network layer，subnets can easily become congested，increasing the delay and（73）for packets. Network designers attempt to avoid congestion by proper desing,Techniques include （74） policy，caching，flow control，and more. The next step beyond just dealing with congestion is to actually try to achieve a promised quality of service. The methods that can be used for this include buffering at the client，traffic shaping，resource（75），and admission control. Approaches that have been designed for good quality of service include integrated services (including RSVP), differentiatd services, and MPLS.

空白处（74）应选择（）

A．abandonment

B．retransmission

C．checksum

D．synchronism