Cloud computing is a phrase used to describe a variety of computing concepts that involve a large number of computers（ ）through a real-time communication network such as the Internet.In science,cloud computing is a（ ）for distributed computing over a network,and means the（ ）to run a program or application on many connected computers at the same time.The architecture of a cloud is developed at three layers:infrastructure,platform,and application,The infrastructure layer is built with virtualized computer,storage,and network resources.The platform layer is for general-purpose and repeated usage of the collection of software resources.The application layer is formed with a collection of all needed software modules for SaaS applications.The infrastructure layer serves as the（ ）for building the platform layer of the cloud.In turn,the platform layer is a foundation for implementing the（ ）layer for SaaS applications.问题1选项A.connectedB.implementedC.optimizedD.Virtualized问题2选项A.replacementB.switchC.substituteD.synonym(同义词)问题3选项A.abilityB.approachC.functionD.method问题4选项A.networkB.foundationC.softwareD.hardware问题5选项A.resourceB.serviceC.applicationD.software