产褥中暑需要与下列哪些疾病进行鉴别：

A．产褥感染

B．产褥期急性乳腺炎

C．晚期产后出血

D．产后子痫

E．以上都不是

The network layer provides services to the transport layer．It can be based on either (67) ．In both cases，its main job is (68) packets from the source to the destination．

In network layer，subnets can easily become congested，increasing the delay and (69) for packets．Network designers attempt to avoid congestion by proper design．Techniques include (70) 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，trafficshaping，resource (71) ，and admission contr01．Approaches that have been designed forgood quality of service include integrated services(including RSVP)，differentiated services，andMPLS．

71（）

A．distribution

B．reservation

C．scheme

D．guarantee