随着我国改革发展越来越进入“深水区”，社会问题越来越多。对于出现的越来越多的社会冲突，许多政府部门或专家采取回避、搪塞或否认的态度进行解释或澄清，而舆论和百姓对这些政府部门或专家的解释、澄清并不买账。这启示我们[ ]

A、要充分发挥人的主观能动性

B、要坚持用变化发展的观点看问题

C、要承认矛盾，积极解决矛盾

D、要坚持具体问题具体分析

Frame Relay is simplified form of (51) , similar in principle to (52) , in which synchronous, frames of data are routed to different destinations depending on header information.

Packets are routed throught one or more Virtual Circuits known as (53) . Most Virtual Circuits are (54) , which means that the network provider sets up all DLCI connections at subscription time. (55) are also part of the Frame Relay specification. They privide a link that only lasts only as long as the session.

（53）是（）

A.DLCIs

B.HDLCs

C.SDLCs

D.DLs