选择题：●A basic premise of OGSA is that everything is (66) by a service:a network enabledentity t

●A basic premise of OGSA is that everything is (66) by a service：a network enabledentity that (67) some capability through the exchange of messages.Computational resources，storage resources，networks，programs，databases，and so forth are all (68) .This adoption of auniform. service-oriented model means that all components of the environment are virtual.Morespecifically，OGSA represents everything as a Grid service：a Web service that conforms (69) a set of conventions and supports standard interfaces for such purposes as lifetime management.This core set of consistent interfaces，from which all Grid services are implemente

D． (70) theconstruction of hierarchical，higher-order services that can be treated in a uniform. way across layersof abstraction.

(66) A．defined

B．represented

C．used

D．passed

(67) A．provides

B．have

C．expands

D．limits

(68) A．elements

B．objects

C．services

D．capability

(69) A．of

B．to

C．as

D．from

(70) A．forms

B．groups

C．consist

D．Facilitates