关于投标联合体说法，正确的是（）。

A.同一专业的单位组成的联合体，按照资质等级较低的单位确定资质等级

B.由同一专业的单位组成的联合体，按照资质等级较高的单位确定资质等级

C.招标人可以在招标公告或招标邀请中要求投标人组成联合体投标

D.招标人不能在招标公告或招标邀请中要求投标人组成联合体投标

E.两个自然人可以组成联合体

The Border Gateway Protocol (BGP) is an interautonomous system. ___49___ protocol. The primary function of a BGP speaking system is to exchange network ___50___ information with other BGP system. This network reachability information includes information on the list of Autonomous System (ASs) that teachability information traverses. BGP-4 provides a new set of mechanisms for supporting ___51___ interdomain routing. These mechanisms include support for advertising an IP ___52___ and eliminate the concept of network class within BGP. BGP-4 also introduces mechanisms that allow aggregation of routes, including ___53___ of AS paths. These changes provide support for the proposed supernettting scheme.

49（）

A.resolving 

B.connecting 

C.supernettting 

D.routing