Cloud computing is a phrase used to describe avariety of computing concepts that involve a large number of computers (71) through a real-time communication network such as the Internet. Inscience,cloud computing is a (72) for distributed computing over a network, and means the (73) 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 infrastucture layer is built with virtualized compute, storage, andnetworkresources.Theplatformlayerisforgeneral-purposeandrepeatedusageofthecollectionofsoftwareresources.TheapplicationlayerisformedwithacollectionofallneededsoftwaremodulesforSaaSapplications.Theinfrastucturelayerservesasthe(74)forbuildingtheplatformlayerofthecloud.Inturn,theplatformlayerisfoundationforimplementingthe(75)layerforSaaS applications.

(71)
A.connected
B.implemented
C.optimized
D.virtualized
(72)
A.replacement
B.switch
C.substitute
D.synonym
(73)
A.ability
B.approach
C.function
D.method
(74)
A.network
B.foundation
C.software
D.hardware
(75)
A.resource
B.service
C.application
D.software